The online computer game “Is this prime?” tests a player’s knowledge of prime numbers—and just surpassed 2,999,999 attempts. Give it a whirl.

The first five prime numbers: 2, 3, 5, 7 and 11. A prime number is an integer, or whole number, that has only two factors — 1 and itself. Put another way, a prime number can be divided evenly ...

From a set of six numbers, use your innovation to identify three whose sum is a perfect square ...

“If you add up all the numbers from 1 to 9, you get 45. 45 is sometimes called a triangular number, or a pyramid number.” The next perfect square year won’t arrive until 2116. Suggest a ...

Multiples and factors - AQA Prime, Square and Cube Numbers. ... There are an infinite number of prime numbers. The prime numbers less than 30 are: 2, 3, 5, 7, 11, 13, 17, 19, 23, and 29.

His idea was to identify all the primes up to a given point by gradually “sieving out” the numbers that aren’t prime. His sieve starts by crossing out all the multiples of 2 (except 2 itself), then ...

Prime numbers, when expressed as that number of dots, can be arranged only in a single row or column, rather than a square or rectangle. David Eppstein/Wikimedia Commons ...