A prime factor is a factor (or divisor) that cannot be divided by another number.So we start with the first prime number 2: 56 / 2 = 28.8 is even, so we can divide by 2 again, 28 / 2 = 14.14 is even so we can again divide by 2 to give 7.We know that 7 is a prime number, so we know that 2 x 2 x 2 x 7 = 56.We can simplify this as when we repeat multiplication, we call this a power, so we can say 23x7 = 56