60 Fun Facts About 4th Grade Math

Which of these numbers is a prime number?

Its only factors are 1 and itself; 4, 6 and 9 can each be made by multiplying two smaller numbers.

A number bigger than 1 that is NOT prime is called what?

Composite numbers such as 8, 9 and 12 can be split into two smaller whole-number factors.

What do we call the distance all the way around the outside of a shape?

You find it by adding up the lengths of every side.

A rectangle is 6 cm long and 4 cm wide. What is its area?

Area of a rectangle is length times width, so 6 × 4 = 24.

A rectangle is 5 m long and 3 m wide. How far is it all the way around the outside?

Add two lengths and two widths: 5 + 5 + 3 + 3 = 16.

In the fraction 3/4, what is the number on top called?

The top number counts how many parts you have; the bottom number tells you how many equal parts make a whole.

Which fraction is greater than 1?

When the top number is bigger than the bottom one, the fraction is 'improper' and worth more than one whole.

How many degrees are in a right angle?

It is a quarter turn, the corner of a sheet of paper or a book.

An angle bigger than a right angle but smaller than a straight angle is called what?

Obtuse means 'blunt'; anything smaller than 90 degrees is acute, meaning 'sharp'.

How many degrees make a full turn all the way around a point?

That is why a compass and a protractor's circle are split into 360 little steps.

An angle that makes a perfectly straight line measures how many degrees?

Half of a full turn is a straight angle.

What do the three angles inside any triangle always add up to?

That is also why a triangle can never have two right angles or two blunt, wide-open angles.

A triangle with three sides all the same length is called what?

All three of its angles are equal too, at 60 degrees each.

A triangle with exactly two sides the same length is called what?

The two angles opposite the equal sides are equal as well.

How many sides does a quadrilateral have?

Squares, rectangles, rhombuses and trapezoids are all quadrilaterals.

How many sides does a hexagon have?

Honeycomb cells and many nuts and bolts are hexagons.

How many sides does an octagon have?

A stop sign is the octagon most kids see every day.

A five-sided shape is called what?

The famous US military headquarters near Washington is named for its five-sided shape.

A closed flat shape made only of straight line segments is called what?

Triangles, squares and hexagons all count; a circle does not, because it has no straight sides.

The distance from the centre of a circle to its edge is called what?

Go all the way across through the centre and you have the diameter, which is twice as long.

If a circle's radius is 5 cm, how wide is it all the way across through the middle?

The diameter goes right across the circle through the middle, so it is two radii end to end.

Two lines that stay the same distance apart and never cross are called what?

Railway tracks and the opposite sides of a rectangle are everyday examples.

Two lines that cross to make right angles are called what?

The corner of a book, a plus sign and the letter T all show it.

A straight path between two endpoints that stops at both ends is called what?

A ray has only one endpoint and goes on forever the other way; a full line has no endpoints at all.

If you can fold a shape so both halves match exactly, the fold is called what?

A capital letter A has one, a square has four, and a circle has endless lines of symmetry.

How many faces does a cube have?

All six faces are identical, like a dice; a cube also has 8 corners and 12 edges.

What is the answer to a multiplication problem called?

Sum is for adding, difference for subtracting, and quotient for dividing.

In the problem 20 ÷ 4 = 5, which number is the quotient?

The 20 being divided is the dividend and the 4 is the divisor.

When you divide 17 by 5, what is the remainder?

5 goes into 17 three times (15), leaving 2 left over.

Which of these is a factor of 12?

12 = 2 × 6, so 6 divides evenly; the full list of factors of 12 is 1, 2, 3, 4, 6 and 12.

Which of these is a multiple of 7?

7 × 6 = 42; a multiple is what you get when you multiply a number by a whole number.

Which of these numbers is even?

An even number can be split into two equal whole halves; 82 = 41 + 41.

9 is a square number because it equals what?

Square numbers can be drawn as a square grid of dots: 1, 4, 9, 16, 25 and so on.

How many groups of four are in 3 × 4 = 12?

Multiplying is repeated adding: 4 + 4 + 4 = 12.

In Roman numerals, what number does IX stand for?

When a smaller symbol comes before a larger one you subtract, so I before X means 10 minus 1.

In Roman numerals, which letter stands for 100?

L is 50, D is 500 and M is a thousand, which is why 2,000 is written MM.

How many metres are in a kilometre?

'Kilo' always means a thousand, so a kilogram is 1,000 grams too.

How many inches are in one foot?

Three feet make a yard, so a yard is 36 inches.

How many feet are in a yard?

A yardstick is three rulers long; 1,760 yards make a mile.

How many ounces are in a pound?

That is why a half-pound burger is 8 ounces.

How many quarts are in a gallon?

A quart is a 'quarter gallon'; there are two pints in each quart.

How many seconds are in one hour?

60 seconds in a minute times 60 minutes in an hour gives 3,600.

How many days are in a leap year?

The extra day is added to February to keep the calendar lined up with the seasons.

How many years are in a century?

Ten decades make a century, and ten centuries make a millennium.

How many items are in a dozen?

Eggs and doughnuts are the classic dozens; half a dozen is 6.

What is a 1 followed by six zeros called?

Written out with commas it is 1,000,000; a billion has nine zeros.

Rounding means changing a number to what kind of value?

Rounding 23.4476 dollars to 23.45 makes it easier to say and write.

In the fraction 3/4, what is the bottom number called?

It tells you the type of parts, like fourths, while the top number counts how many of them there are.

In a number like 25.97, what is the dot between the 5 and the 9 called?

Some countries use a comma instead of a dot for the same job of separating whole numbers from parts.

How many grams are in one kilogram?

Kilo means one thousand, which is why a kilometre is also one thousand metres.

How many cubic centimetres fit inside one litre?

A litre is a cube measuring 10 cm on each side, and a litre of water weighs almost exactly one kilogram.

How many years are in a millennium?

Ten centuries make one millennium; the year 2000 was celebrated as the start of a new one.

How many corners, or vertices, does a cube have?

A cube also has twelve edges of equal length that form its six square faces.

How many flat, parallel faces does a solid cylinder, like a tin can, have?

The rest of its surface is one curved side; the two flat faces are usually circles.

What do you call a three-sided shape that has one 90-degree angle?

Two of its sides are perpendicular, and the longest side opposite the right angle is called the hypotenuse.

What is a four-sided shape with all four sides the same length called?

A rhombus is sometimes called a diamond, and a square is a rhombus whose angles are all right angles.

At what temperature does water boil on the Fahrenheit scale?

Water freezes at 32 °F, so the two points sit exactly 180 degrees apart on that scale.

In Roman numerals, what number does MM stand for?

Roman numerals add symbols together and have no symbol for zero.

What is the result when you multiply anything by 1?

Mathematicians call 1 the multiplicative identity because of this property.

How can you tell whether a whole number is even just by looking at it?

Zero itself counts as even, and any two numbers next to each other on the number line have opposite parity.