We've got two numbers: 7936 and 4002. Let's find their sum.

Step 1: We'll start by adding the digits 6 & 2 in column 1 and get 8.

Step 2: We'll start by adding the digits 3 & 0 in column 2 and get 3.

Step 3: We'll start by adding the digits 9 & 0 in column 3 and get 9.

Step 4: We'll start by adding the digits 7 & 4 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 7936 + 4002 = 11938.

