119 Fun Facts About Pi

A famous run of six consecutive 9s in the decimal expansion of π starts at roughly which decimal place?

The six consecutive 9s begin at the 762nd decimal place of π, a run nicknamed the Feynman point after Richard Feynman, who joked he wanted to memorize π that far and then say 'and so on'.

Which Welsh mathematician first used the Greek letter π for the circle constant, in a 1706 book?

William Jones printed π in his 1706 Synopsis Palmariorum Matheseos but credited its formulas to the 'ready pen' of John Machin, so some suspect Machin wrote the symbol first.

Which mathematical property of pi means its decimal expansion is infinite and non-repeating?

Irrational numbers cannot be written as one whole number over another; every such fraction's decimal either stops or repeats, as 1/3 = 0.333... does, so π's never can.

Pi is transcendental: not the root of any non-zero polynomial with which type of coefficients?

Rational coefficients are the test: √2 solves x² − 2 = 0, so it is merely algebraic, while π solves no such equation; Cantor showed in 1874 that almost all numbers are like π.

Pi Day is celebrated annually on which date?

March 14 is written 3/14 in American date order, matching π's first three digits; the day began in 1988 as a staff party at a science museum, with fruit pies and tea.

Which Greek mathematician approximated Pi by inscribing and circumscribing polygons?

Archimedes trapped π between polygons drawn inside and outside a circle, doubling their sides up to 96; later calculators kept refining his method for well over a thousand years.

What are the first five digits after the decimal point of π?

14159 follows the 3; the old mnemonic 'How I want a drink, alcoholic of course' hides the digits in the number of letters of each word: 3, 1, 4, 1, 5, 9.

Pi appears in which famous mathematical equation involving 'e', 'i', and '1'?

Euler's Identity, e^(iπ) + 1 = 0, is prized for economy: it ties together five fundamental constants using one addition, one multiplication and one exponentiation, and nothing else.

Roughly how many digits of π did Rajveer Meena recite for his 2015 Guinness World Record?

70,000 digits is the Guinness record: Rajveer Meena recited them blindfolded at a university in Vellore, India, in a session that lasted nearly ten hours.

A clay tablet more than 3,500 years old shows which ancient civilisation taking π as 3.125?

Babylonians usually made do with a plain 3 for circle sums, but this one tablet works with 3 1/8, only about half a percent below the true value.

Which Egyptian papyrus, a set of maths problems copied by the scribe Ahmes, implies π is about 3.16?

The Rhind Papyrus takes eight-ninths of a circle's width and multiplies it by itself to get the area; a Scottish collector, Alexander Rhind, bought the scroll in Luxor in 1858.

Which ancient text describes a round basin ten cubits across and thirty around, implying π = 3?

The Bible's First Book of Kings gives Solomon's temple a cast 'molten sea' of those dimensions; read literally that makes π exactly 3, most likely a craftsman's round measurement, not a formula.

Which construction is impossible with compass and straightedge because Pi is transcendental?

Squaring the circle kept tempting amateurs even after the proof that it can't be done: false 'solutions' went on arriving for generations.

Which solid has a volume of (4/3)πr³?

A sphere's volume is (4/3)πr³, so doubling the radius multiplies the volume by eight: a 20 cm ball holds as much as eight 10 cm ones.

Pi Approximation Day honours which common fractional approximation of π?

22/7 gives the day its date, 22 July, in day-first notation; the fraction is actually a slightly closer match for π than the more familiar 3.14.

Which mathematician popularised the symbol π for the circle constant, without being the first to use it?

Leonhard Euler took up the symbol in the 1730s, and his widely read 1748 textbook Introductio in analysin infinitorum, along with a vast correspondence, spread it across Europe.

Pi Day was first celebrated in 1988 at the Exploratorium, a science museum in which US city?

San Francisco's Exploratorium started it as a staff get-together; physicist Larry Shaw, later nicknamed the Prince of π, led the museum's Pi Day parades every year until his death in 2017.

Which Persian astronomer computed π to 16 decimal digits in 1424, a record for about 180 years?

Jamshid al-Kashi, working at Samarkand, computed 2π to nine sexagesimal (base-60) places in 1424, equivalent to 16 decimal digits, using a polygon of 3×2^28, more than 800 million, sides.

The Greek letter π corresponds to which letter of the Latin alphabet?

P is the Latin counterpart of π; the symbol was most likely picked as the initial of a Greek word for a circle's edge, 'periphery' or 'perimeter'.

Which Indian mathematician published a set of strikingly fast-converging formulae for π in 1914?

Srinivasa Ramanujan's 1914 paper gave a series that adds about eight correct digits of π with every term; his formulae became the basis of the fastest methods used for later record computations.

The alternating sum π/4 = 1 − 1/3 + 1/5 − 1/7 + ... usually goes by which name?

The Gregory-Leibniz series is lovely but nearly useless for calculation: thousands of terms are needed to get just four correct decimals of π.

In which 1960s TV series is a murderous entity foiled by ordering a computer to compute π to its last digit?

Star Trek's 1967 episode 'Wolf in the Fold' has Spock give the order; because π never ends, the impossible job ties up the computer that the entity had taken over.

Which famous physicist's birthday falls on Pi Day?

Albert Einstein was born in Ulm, Germany, in 1879; Princeton, New Jersey, his home for more than twenty years, has marked the day with Einstein look-alike contests.

Chinese mathematicians in the 5th century AD approximated Pi to how many decimal places?

In the 5th century AD, Chinese mathematicians, notably Zu Chongzhi, approximated Pi to seven decimal places.

William Shanks hand-calculated 607 digits of π in 1853; at roughly which digit did his error begin?

Shanks's error began at the 528th decimal place, so every later digit, including the 100 he added in 1873 to reach 707, was wrong; D. F. Ferguson spotted the mistake with a mechanical desk calculator in 1944.

How much longer must a rope around Earth's equator be to hover one metre above the ground all the way round?

About 6 metres, or 2π times the one-metre lift, is all it takes; Earth's size drops out of the sum, so the answer would be the same for a football.

Which 18th-century polymath, whose name is on a map projection, first proved that π can't be written as a fraction?

Johann Heinrich Lambert proved it in the 1760s using a continued fraction for the tangent function; his conic map projection of 1772 is still used for aeronautical charts.

What is the definition of the circumference of a circle?

The distance around it is a circle's circumference; Eratosthenes worked out Earth's in the third century BC by comparing noon shadows in two Egyptian cities.

In the cylinder volume formula V = πr²h, what does 'h' represent?

In the formula for the volume of a cylinder, V = πr²h, 'h' stands for the height of the cylinder.

In 1897 an amateur mathematician nearly got which Midwestern US state's legislature to pass a bill implying π = 3.2?

Indiana's House passed the bill without a single vote against; the state Senate then postponed it indefinitely, so the wrong value never became law.

Which fraction, accurate to six decimals, did Zu Chongzhi call the milü ('close ratio') around 480 AD?

355/113 was Zu Chongzhi's 'close ratio'; no fraction with a smaller denominator comes nearer to π, and nobody anywhere computed a better value for at least 800 years.

Ludolph van Ceulen's 35 decimals of π, his life's work, were engraved on his tombstone in which Dutch city?

Leiden's Pieterskerk held the stone, which vanished around 1800 and was replaced by a replica two centuries later; Germans long called π the Ludolphine number in his honour.

In which Alfred Hitchcock Cold War thriller is π the secret sign of an East German escape network?

Torn Curtain (1966) has Paul Newman's scientist scratch a π in the dirt outside a farmhouse to signal the underground network that smuggles fugitives to the West.

In the pendulum period formula T = 2π√(L/g), what does L stand for?

L is the length of the pendulum: for small swings the period T = 2π√(L/g) depends only on length and the local gravity g, not on the mass or the amplitude.

Which structure's perimeter divided by twice its height is claimed, debatably, to approximate Pi?

The Great Pyramid of Giza was planned 440 cubits wide and 280 high, and those round numbers give the ratio; its faces follow a builders' slope of 5½ palms across for each cubit up.

How did Zacharias Dase produce his record 200 decimals of π in 1844?

Entirely in his head, in about two months: Zacharias Dase was a touring calculating prodigy who also multiplied two 100-digit numbers mentally, taking under nine hours.

In the equation e^(iπ) + 1 = 0, what is the constant i called?

The Imaginary Unit i is defined by i² = −1; René Descartes coined 'imaginary' in the 1600s for roots that, he said, matched no real quantity, and the name stuck.

A 1995 poem that hides 740 digits of π in its words' letter counts retells which American poet's 1845 poem?

Edgar Allan Poe's 'The Raven' is retold in Mike Keith's 'Near a Raven', where each word's letter count is the next digit of π; Keith later stretched the trick to nearly 4,000 digits.

The density of which probability distribution contains the factor 1/√(2π)?

The normal (Gaussian) distribution's density is (1/(σ√(2π))) exp(−(x−μ)²/2σ²); the √(2π) comes from the Gaussian integral ∫e^(−x²/2)dx = √(2π), which makes the total probability equal 1.

Which property of π's decimal digits is widely believed but still unproven?

They appear equally often, or very nearly, in every long stretch checked so far, yet no proof exists; it is not even proven that every digit keeps turning up forever.

Which formula gives the total surface area of a closed cylinder?

2πr² + 2πrh counts the two circular ends plus the curved side, which unrolls into a rectangle as long as the circumference, 2πr, and as tall as the cylinder, h.

The classical polygon method of approximating pi began by inscribing which polygon in a circle?

A hexagon was the natural start because its side exactly equals the circle's radius; four doublings then give the 96-sided polygons that fixed π at about 3.14.

Which brothers computed two billion digits of π on a supercomputer they built in a Manhattan apartment?

The Chudnovsky brothers built the machine, which they called m zero, from mail-order parts in what had been one brother's living room.

Overclockers race the benchmark Super PI, which times a PC computing digits of π, mainly to test which component?

Processor speed is the point: Super PI is a port of the program written for a 1995 record run by Japan's Yasumasa Kanada, and overclockers compare how fast their chips finish it.

Which Gupta-era Indian mathematician gave a strikingly accurate value of π in an astronomical treatise of 499 AD?

Aryabhata's Aryabhatiya puts the circumference of a circle 20,000 units across at 62,832 and calls the figure 'approaching', a word some read as a sign he knew it could never be exact.

Which scientist computed about 15 digits of π in the 1660s and admitted to being 'ashamed' of carrying the sum so far?

Isaac Newton did the sum with his new infinite series, then confessed he was ashamed to say how many figures he had carried it to, 'having no other business at the time'.

A maths joke says which food, with radius z and thickness a, has a volume that spells its own name?

Pizza works because a flat cylinder's volume is π times radius squared times thickness: with radius z and thickness a, that reads pi·z·z·a.

A retired engineer from which country recited 100,000 digits of π from memory in 2006, a feat Guinness never validated?

Japan's Akira Haraguchi needed about sixteen and a half hours at a public hall near Tokyo; he has likened reciting the digits to chanting a Buddhist mantra.

Which French naturalist showed that needles dropped on a floor of ruled lines can be used to estimate π?

The Comte de Buffon, better known for a 36-volume natural history, worked out that the chance of a needle crossing a line depends on π, so counting crossings gives an estimate.

Which equations of physics carry an 8π in the constant linking matter to the curvature of spacetime?

The Einstein field equations multiply the density of matter and energy by 8πG/c⁴; that value is exactly what makes weak gravity match the classical inverse-square law.

Pi (π) is defined as the ratio of a circle's circumference to its what?

Diameter is the divisor: wrap a string round any circular plate and it spans the plate's width three times with a little to spare, whatever the plate's size.

In the Greek alphabet, the letter π comes directly before which letter?

Rho comes next; an early Greek letter, qoppa, once stood between the two, and though the Greeks dropped it from the alphabet, it survives as the Latin Q.

John Machin's fast-converging formula of 1706 made him the first person to compute π to how many decimal places?

100 decimal places fell to Machin's formula; variations on it stayed the standard way to compute π for some 250 years, well into the age of computers.

John Wallis, whose 1650s formula builds π from a never-ending product of fractions, also introduced which symbol?

∞ (infinity) entered mathematics in Wallis's treatise on conic sections; why he picked that shape is uncertain, though one theory traces it to an old Roman way of writing 1,000.

In which animated series does a shopkeeper boast in court of being able to recite π to 40,000 decimal places?

The Simpsons has Apu make the claim in 'Marge in Chains' and add, correctly, that the last digit is 1; the writers had asked a NASA mathematician, who sent a 40,000-digit printout.

What is the surface area of a sphere of radius r?

A sphere's surface is 4πr², exactly four times the area of the flat circle through its centre; double the radius and the surface grows fourfold.

Estimating π by scattering random points over a square and counting those inside a circle is which kind of method?

Monte Carlo methods lean on chance and are named after the Monaco casino where Stanisław Ulam's uncle gambled; the share of points landing inside the circle approaches a quarter of π.

Which Greek letter names 2π ≈ 6.283, promoted by some as the better circle constant?

Tau (τ) equals 2π ≈ 6.283, the ratio of a circle's circumference to its radius; Michael Hartl's 2010 'Tau Manifesto' argued for it, and Tau Day is marked on 28 June (6/28).

The Gauss–Legendre algorithm computes π by iterating which kind of mean?

The arithmetic–geometric mean of 1 and 1/√2 drives it: each pass roughly doubles the count of correct digits, so 25 passes are enough for 45 million digits of π.

Roughly how many decimal places of π fix the observable universe's circumference to within a hydrogen atom?

About 40 decimals do it, and NASA's own sum makes it 37; the agency steers interplanetary spacecraft with just 15.

How many degrees are equal to π radians?

π radians equal 180 degrees, because a full turn of 360 degrees is 2π radians, the circumference of a unit circle divided by its radius.

Which function's Taylor series, at x = 1, gives π/4 = 1 − 1/3 + 1/5 − 1/7 + ...?

Because arctan(1) = π/4, plugging x = 1 into x − x³/3 + x⁵/5 − ... gives the series. Using arctan values at smaller arguments (Machin's formula) converges far faster and was how π was computed for two centuries.

Whose 1873 proof that e is transcendental was adapted nine years later to prove π transcendental?

Charles Hermite proved in 1873 that e is transcendental, the first number shown to be so that had not been constructed for the purpose; the same technique, extended nine years later, settled π as well.

Which German mathematician proved in 1882 that pi is transcendental?

Ferdinand von Lindemann proved π transcendental in 1882, confirming a conjecture Legendre had made in 1794, the year he showed π² is irrational; the Lindemann–Weierstrass theorem generalised the result three years later.

Which pioneering electronic computer set a π record in 1949 by calculating 2,037 decimal places?

ENIAC's 2,037 digits nearly doubled the 1,120 that two men with a desk calculator had reached earlier that year; no record since has been set without a computer.

Who computed pi to 100 trillion digits in 2022?

Emma Haruka Iwao, a Google developer advocate, computed 100 trillion digits on Google Cloud in 2022 using Alexander Yee's y-cruncher program, three years after her own 31.4-trillion-digit record of 2019.

The Basel problem's celebrated solution showed that 1 + 1/4 + 1/9 + 1/16 + ... adds up to what?

π²/6 links pi to the primes: the chance that two random integers share no common factor is 6/π², about 61 percent.

The 'pi room', ringed with 707 digits of π, is a feature of a science museum founded in 1937 in which city?

Paris's Palais de la Découverte copied the digits from William Shanks's hand calculation of 1873; roughly the final quarter proved wrong, and the wall was corrected in 1949.

In which 1985 novel is a message from the universe's creator hidden in the digits of pi?

In Carl Sagan's 1985 novel Contact, the heroine finds a pattern hidden deep in the digits of π, a plot point dropped from the 1997 film starring Jodie Foster.

Which Star Trek character thwarts an evil entity by ordering the computer to calculate pi to its last digit?

Mr Spock knew the sum could never finish, so the entity possessing the Enterprise's computer was swamped. The 1967 episode is 'Wolf in the Fold'.

Which British physicist died on Pi Day in 2018, at the age of 76?

Stephen Hawking died at his Cambridge home, having lived more than 50 years after his diagnosis of motor neurone disease.

Which tech company sold a number of shares matching the digits of pi in a 2005 stock offering?

Google announced the pi-themed sale a year after it first went public, another maths joke in its share filings.

Dutch fencing teacher Ludolph van Ceulen's digits of pi were engraved on what after his death?

His tombstone in Leiden displayed the 'Ludolphine number'; the stone was later lost and only restored in 2000.

What happens to the value of pi when a circle is drawn twice as wide?

It stays the same: a circle twice as wide is also twice as far around, which is why pi works for a coin and a Ferris wheel alike.

In the writing style called Pilish, which feature of each successive word matches the digits of pi?

Its number of letters is the code, so 'How I need a drink' gives pi's opening digits. Mike Keith's novel Not A Wake keeps it up for 10,000 of them.

Which Simpsons character silences a noisy hall of scientists by shouting that pi is exactly three?

Professor Frink uses the line to win the room's attention at his own science conference in 'Bye Bye Nerdie'; the whole crowd gasps.

NASA's Jet Propulsion Laboratory navigates spacecraft between planets using pi rounded to which decimal place?

The 15th decimal is all JPL needs: a circle billions of miles wide, drawn around Voyager 1, would be off by about half an inch.

Which digit is the last to show up in pi, first appearing at the 32nd decimal place?

Zero is missing from pi's first 31 decimals, by which point every other digit has appeared at least twice.

Which American university has traditionally released its admissions decisions on Pi Day?

MIT began posting its decisions online at 6:28 pm on Pi Day in 2012, a time picked to honour a rival circle constant as well.

Which Simpsons character testifies in court to being able to recite pi to 40,000 decimal places?

Apu adds, correctly, that the 40,000th digit is a one. The show's writers had asked a NASA researcher, who posted them a printout of all 40,000.

The formula V = πr²h/3, one third of a matching cylinder's volume, describes which solid shape?

Cone volumes are a third of a cylinder's on the same base, so three full ice-cream cones of water exactly fill one matching tin.

Using 3.14 for pi, a wheel 10 metres across rolls roughly what distance in one full turn?

31.4 m is simply pi times the width; by the same rule the London Eye, 120 metres across, carries its riders about 377 metres per lap.

Which Canadian author wrote Life of Pi, whose shipwrecked hero takes his nickname from the number?

Yann Martel's hero, Piscine Patel, spends 227 days adrift in a lifeboat with a Bengal tiger called Richard Parker.

Who directed the 1998 thriller Pi, about a number theorist hunting for patterns in the stock market?

Darren Aronofsky made Pi as his first feature and won the Directing Award at Sundance for it. Its hero's machine spits out a mysterious 216-digit number.

Which English singer recites more than a hundred decimals of pi in a track on the 2005 album Aerial?

Kate Bush sings pi to its 78th decimal place, then skips ahead to the 101st and carries on to the 137th.

Which Italian mathematician computed pi as 3.1418 around the year 1220, using a polygon method?

Fibonacci, better known for the number sequence he drew from breeding rabbits, got there with a polygon method he devised on his own.

Which American gymnast was born on Pi Day in 1997, in Columbus, Ohio?

Simone Biles spent part of her early childhood in foster care before becoming the most decorated gymnast in history.

Heisenberg's uncertainty principle, with 4π in its formula, limits knowledge of which pair of particle properties?

Position and momentum cannot both be pinned down: the product of their uncertainties never drops below Planck's constant divided by 4π.

Which UN agency designated Pi Day as the International Day of Mathematics at its 2019 general conference?

UNESCO adopted the day in November 2019, turning a pun-filled museum party from San Francisco into an official worldwide observance.

A round basin whose measurements imply that pi equals three is described in which book of the Hebrew Bible?

1 Kings gives the basin at Solomon's Temple as ten cubits across and thirty around; one rabbi argued the thickness of its rim explains the gap.

Whose typesetting system TeX has version numbers that add one more digit of pi with each update?

Donald Knuth has said the final change, made after his death, will set the version to pi itself, turning every remaining bug into a feature.

The Chudnovsky brothers computed two billion digits of pi in the early 1990s on a supercomputer built where?

A Manhattan apartment housed the machine, which the two brothers assembled themselves and nicknamed 'm-zero'.

Which astronomer of Roman-era Alexandria used the fraction 377/120 as his approximation of pi around 150 AD?

Ptolemy's fraction, set down in his Almagest, was the first known approximation of pi to be accurate to three decimal places.

A 1998 April Fools' hoax claimed which American state had voted to change pi to the 'Biblical value' of 3?

Alabama lawmakers took protest calls before the joke was revealed; physicist Mark Boslough wrote it to mock a creationism push in New Mexico.

Which British savant recited 22,514 digits of pi from memory on Pi Day 2004, a European record?

Daniel Tammet took five hours and nine minutes over the recital, and later told his story in the memoir Born on a Blue Day.

The formula πab, where a and b are the two semi-axes, gives the area enclosed by which curve?

Ellipse areas follow the circle's rule: make the two semi-axes equal and πab collapses back to the familiar π times r squared.

Pi begins 3.243F6A88 when written in which numeral system?

Hexadecimal is base 16, so the characters A to F stand in for the values ten to fifteen and pi appears to contain an F.

Pi times ten million comes within half a percent of the number of what in one calendar year?

Seconds in a Gregorian year total 31,556,952, so pi times ten million falls short by only about 141,000 of them.

Pi squared, about 9.87, nearly matches the value in SI units of which everyday physical quantity?

Earth's surface gravity is about 9.81 metres per second squared. Had the metre been defined by a pendulum swinging once a second, as proposed in 1790, it would be exactly pi squared.

In number theory, the function written π(x) counts which kind of integers up to a given value x?

Prime numbers thin out as x grows, and π(x) keeps the tally: there are 25 of them below 100 but only 168 below 1,000.

Sine and cosine repeat every 2π, but which trigonometric function repeats twice as often, every π?

Tangent repeats after only half a turn, because a line through the origin points the same way once it is rotated by π.

In 1991 David Boll found the digits of pi emerging from iteration counts in which famous fractal?

The Mandelbrot set surprised Boll near its 'neck' at −0.75: the closer he probed, the more the step counts spelled out pi.

The Greek letter pi descends from the Phoenician letter pe, thought to have begun as a picture of what?

A mouth is the usual reading of the original pictogram, and 'pe' is to this day the Hebrew word for one.

The run of six 9s in pi's decimals is nicknamed after which American physicist, who reputedly joked about it?

Richard Feynman reputedly wanted to recite pi as far as the nines and finish 'and so on', but nobody has traced the lecture where he said it.

Mike Keith rewrote which Edgar Allan Poe poem so that its words encode the digits of pi?

The Raven became 'Near a Raven', which Keith later reworked into the opening of his short story Cadaeic Cadenza.

Which company's 7090 mainframe pushed the record for digits of pi into six figures in 1961?

IBM's machine in New York needed 8.7 hours for the run, which is credited to Daniel Shanks and John Wrench.

Retired engineer Akira Haraguchi claimed in 2006 to have recited pi from memory to which number of decimal places?

100,000 decimal places took him about 16 hours, but Guinness World Records never verified the Japanese engineer's claim.

Which 3rd-century Chinese mathematician approximated pi using a polygon with 3,072 sides?

Liu Hui devised a repeatable polygon algorithm, which Zu Chongzhi later pushed to 12,288 sides for an even finer value.

Which Indian founder of the Kerala school estimated pi to 11 digits around 1400 using infinite series?

Madhava's series for sine and cosine are known mainly because later Kerala scholars such as Nilakantha credited them to him.

The Bailey–Borwein–Plouffe formula of 1995 first made which feat possible with pi's digits?

Finding one without earlier ones works in base 16 rather than base 10, yet it lets record-setters spot-check a few far-off digits of a new result.

Which English astronomer devised the pi memory aid that begins 'How I want a drink, alcoholic of course'?

James Jeans ended the sentence 'after the heavy lectures involving quantum mechanics', which carries the trick on for fifteen digits in all.

Which physicist, nicknamed the 'Prince of Pi', founded Pi Day while working at a San Francisco science museum?

Larry Shaw spent 33 years at the museum and proclaimed 2015, written 3/14/15, the 'Pi Day of the Century'.

Stirling's approximation, built around the square root of 2πn, estimates which rapidly growing function of n?

The factorial multiplies together every whole number up to n, yet pi turns up in its estimate with no circle anywhere in sight.

Until 2019, which constant of electromagnetism was defined as exactly 4π × 10⁻⁷ henries per metre?

Vacuum permeability lost its exact value when the SI units were revised in 2019; ever since, it has had to be determined by experiment.

Which medieval Italian poet apparently worked with the value 3 + √2/10, about 3.14142, for pi?

Dante's value falls short of pi by only about 0.005 percent, a slip of 17 centimetres on a circle one kilometre wide.

Eating pie on Pi Day is a pun that works because 'pi' and 'pie' are which kind of word pair?

Homophones sound alike but differ in spelling or meaning, and it helps the joke that so many pies happen to be round.

John Wrench and Levi Smith reached a record 1,120 digits of pi in 1949 using which tool?

A desk calculator took the pair to 1,120 digits, the last record of its kind set by people punching keys rather than writing programs.

Six times pi to the fifth power lands within 0.002 percent of which quantity in particle physics?

Proton-to-electron mass ratio is about 1836.15, while six times pi to the fifth gives 1836.12; the near miss was first pointed out in 1951.

A much-repeated claim, not borne out by later studies, says the average winding ratio of what equals pi?

Rivers were said to wander about pi times the straight-line distance from spring to sea, a neat idea from 1996 that later measurements did not support.