We have numbers 7121 and 9761. Let's start adding them together.

Step 1: We'll start by adding the digits 1 & 1 in column 1 and get 2.

Step 2: We'll start by adding the digits 2 & 6 in column 2 and get 8.

Step 3: We'll start by adding the digits 1 & 7 in column 3 and get 8.

Step 4: We'll start by adding the digits 7 & 9 in column 4 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

So, 7121 + 9761 = 16882.

