Prime Numbers
⭐ MasteredA prime number can only be divided evenly by 1 and itself. 2, 3, 5, 7 and 11 are primes.
2 is the only even prime number.
All about Prime Numbers
A prime number is a whole number greater than 1 that has exactly two factors: 1 and itself. The first few primes are 2, 3, 5, 7, 11, 13 and 17. Numbers with more than two factors are called composite numbers.
The number 2 is the only even prime, because every other even number can be divided by 2. Prime numbers are the building blocks of all whole numbers, since every number can be written as a product of primes.
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Real-life uses of Prime Numbers
- Keeping secret codes safe, because computers use very large primes for encryption
- Splitting a group into equal teams only when the number is not prime
- Solving puzzles and number games
Frequently asked questions about Prime Numbers
Is 1 a prime number?
No. A prime needs exactly two different factors, and 1 has only one.
What is the biggest known prime?
Mathematicians keep finding larger primes using computers. The largest known prime has millions of digits.
How can you tell if a number is prime?
Check whether any number from 2 up to its square root divides into it exactly. If none does, it is prime.