By how much is the product of 27 and 13 greater than their sum?

Well its quite simple...
the product of 27 and 13 is 351 (which is found by multiplying 27 and 13)
and the sum of 27 and 13 is 40 (which is found by adding 27 and 13 together)

therefore to work out the difference you have to do:
351 - 40 which equals 311

so 311 is your answer 

Product : - 27 * 13 = 351
Sum = 27 + 13 = 40

Thus, difference = 351 - 40  = 311

Thus, the product of 27 and 13 is 311 numbers greater than the product.