Before we begin to answer this question we need to have a clear idea of what a prime number is: A prime number is a number greater than 1 that cannot be found by multiplying 2 smaller numbers. To answer this question we need to keep dividing by the lowest possible prime factor that gives a whole number as a result. It maybe sounds a little dense in words, lets look at the question. The lowest prime factor for 156 is 2: 156/2= 78. We can divide by 2 again: 78/2=39. Now we can't divide by 2 anymore, lets try 3: 39/3= 13. 13 is already a prime number telling us we can't go any further. So 156 written as a product of its prime factors is: 22 x 3 x 13