The prime factor of a number is simply the prime numbers capable of multiplying together to make the original number. Factors are just numbers that can be multiplied together to get another number but prime factors are made up only of prime numbers. For example, the factors of 15 are 1, 3, 5, and 15.. These are the numbers that can be multiplied to give the value 15 but of these numbers, only 3 and 5 are prime factors as they are the only prime numbers present. The prime factor of 24 therefore are 2 and 3 as these are the prime numbers that can be multiplied by themselves to give the value 24 i.e. 2×2×2×3=24