Q 01/05

Brahmagupta called numbers above zero fortunes; what money word did he use for numbers below zero?

A) Debts

B) Taxes

C) Thefts

D) Wagers

Answer · why

A) Debts

Debts were his picture of numbers below zero, and the image made the rules easy to follow. Take a debt away from nothing, he wrote, and you are left w...

Q 02/05

Brahmagupta's multiplication method gomutrika takes its name from the trail of urine left by which animal?

A) Dog

B) Goat

C) Cow

D) Horse

Answer · why

C) Cow

Cow urine gave gomutrika its name, yet the method itself is close to the long multiplication taught in schools today. It sets out shifted rows of part...

Q 03/05

Which of Brahmagupta's rules for calculating with zero is the one that modern mathematics rejects?

A) 0 + 0 = 0

B) 0 − 0 = 0

C) 0 × 0 = 0

D) 0 ÷ 0 = 0

Answer · why

D) 0 ÷ 0 = 0

0 ÷ 0 = 0 was his answer, where mathematicians now call that division undefined. The other three rules shown here, set down in 628, are still taught t...

Q 04/05

Brahmagupta wrote that it is the earth's nature to attract and keep things, describing which force?

A) Magnetism

B) Gravity

C) Friction

D) Buoyancy

Answer · why

B) Gravity

Gravity was a pull in his account: heavy things fall to the earth, he wrote, by a law of nature. He set that hold beside the way water naturally flows...

Q 05/05

Brahmagupta's great treatise has no mathematical symbols because the whole book is written in what?

A) Verse

B) Dialogue

C) Riddles

D) Letters

Answer · why

A) Verse

Verse carries the entire work, so every rule and every number is spelled out in words. Even so, it holds the first clear description of a formula taug...