What is the sum of 15 and 27?

To determine the sum of 15 and 27, you simply add the two numbers together. Starting with 15, when you add 27, you can think of it in parts:

First, add 15 and 20, which equals 35. Then, you add the remaining 7 to that sum. So, 35 + 7 = 42.

Thus, the total sum of 15 and 27 is 42. This makes it clear why that answer is correct as you directly arrive at the total by performing the addition operation accurately.