Let's break this down. We're going to add 691 and 156 together.

Step 1: We'll start by adding the digits 1 & 6 in column 1 and get 7.

Step 2: We'll start by adding the digits 9 & 5 in column 2 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 6 & 1 in column 3 and get 8.

So, 691 + 156 = 847.

