About Prime Numbers and Factors Quiz
A prime number can be divided evenly only by 1 and itself, and the Prime Numbers and Factors Quiz makes a daily game of telling primes from the rest. Easy questions ask which number is prime, which prime comes next, which number is a factor of another and what a number squared is. Medium ones find the number that is not prime, the greatest common factor and least common multiple of two numbers, square roots and how many factors a number has, and the hard ones ask for prime factorizations and spot primes above 100. The computer works out every question exactly, and each explanation shows the factors that decide it.
How to play Prime Numbers and Factors Quiz
- Press Start for the first of ten questions. The clock starts with it and stops at your last answer.
- Each question asks about primes, factors, multiples, squares or square roots: which number is prime, a greatest common factor, a least common multiple or a prime factorization.
- Tap an answer, or press 1 to 4 (or A to D) on a keyboard. Answers are final: you see the right one and a one-line explanation, then press Next.
- Most correct answers ranks first, then the fastest time. Only a member’s first finished quiz of the day counts for the leaderboard.
Tips & strategy
- To test a number, divide it only by the primes up to its square root: to check 97, try 2, 3, 5 and 7.
- Apart from 2 and 5 themselves, no prime ends in 0, 2, 4, 5, 6 or 8, and a number whose digits add up to a multiple of 3 is divisible by 3.
- Watch the look-alikes: 91 = 7 × 13, 119 = 7 × 17 and 221 = 13 × 17 are not prime.
Prime Numbers and Factors Quiz: questions and answers
Is 1 a prime number?
No. A prime has exactly two different factors, 1 and itself, and 1 has only one, so the smallest prime is 2.
What is the difference between a factor and a multiple?
A factor divides a number evenly, as 3 divides 12; a multiple is the number times a whole number, as 12 is a multiple of 3.
Are the Prime Numbers and Factors Quiz questions ever the same?
The questions are made by the computer for each day, from simple warm-ups to hard ones, so there is a new set every day. Everyone gets the same ten on the same day.