A Numbers Game Trivia Quiz

Answer: 6

Used almost universally across the world, our base 10 numbering system is so named because there are 10 single-digit numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. Three others are listed as decoy answers.

Answer: 57

An odd number can be written in the form 2n+1, where n is some integer. For instance, 57 = 2*28+1. Two decoy answers are odd.

Answer: 2

A prime number has exactly two distinct factors (one and itself). 5 is the only decoy answer. Even answers (except 2) can be ruled out immediately, while 57 = 3*19 and 35 = 5*7.

Answer: 35

6*6 = 36, so 35 is one less than a square number. The name "square number" is chosen to indicate a geometric interpretation: for instance, a 6x6 square grid contains 36 small squares.

Some numbers that would fit, those of the form n^2 - 1, are 0, 3, 8, 15, 24, 48 and 63, of which only 8 is a possible answer.

Answer: 50

7*7 = 49, so 50 is one more than a square number. Some numbers that would fit, those of the form n^2 + 1, are 2, 5, 10, 17, 26, 65, of which 2 and 5 were decoy answers.

Answer: 56

7*7 = 49 and 49 + 7 = 56. The operations "squaring" and "square rooting" are inverses: when applied in either order to a positive number, they cancel each other out. Each number really has two square roots (for example, (-7)*(-7) = 49 and 7*7 = 49), but when uniqueness is implied (such as "the square root") only the non-negative number is meant.

Numbers that could fit, those of the form n^2+n, include 6, 12, 20, 30, 42 and 72, of which 6 is presented as a decoy.

Answer: 8

2*2*2 = 8 is the only cube number given as an option. Like square numbers, there is a geometric interpretation: a cube with two rows, two columns and two layers of depth contains 8 small cubes.

Answer: 100

The American mathematician Edward Kasner was looking for a name for this large number while on a walk with his nine-year-old nephew, who suggested "googol". The name was later adopted (and spelling deliberately changed) by the search engine "Google", to indicate the vastness of the internet.

Answer: 18

From 1 million (6 zeroes) upwards, adding three zeroes (i.e. multiplying by a thousand) takes you to the next number: billion, trillion, quadrillion, quintillion, sextillion, septillion, octillion, nonillion and so forth. A quintillion is thus 10^18, a 1 followed by 18 zeroes.

Interestingly, this answer is not necessarily uniquely correct, though it is unique among the options given. There exists a long scale - sometimes called the "British system", despite being rare in Britain today - in which the naming system goes up by the millions rather than the thousands. There, a quintillion is a 1 followed by 30 zeroes.

Answer: 5

Used in many parts of the world, the "Indian system" of numbering does not use "million", "billion" and so forth. It uses a lakh (one hundred thousand), written 1,00,000, and a crore (ten million), written 1,00,00,000.