We've got two numbers: 7001 and 7971. Let's find their sum.

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 0 & 7 in column 2 and get 7.

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

Step 4: We'll start by adding the digits 7 & 7 in column 4 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

So, 7001 + 7971 = 14972.

