We've got two numbers: 2007 and 3131. Let's find their sum.

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

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

Step 3: We'll start by adding the digits 0 & 1 in column 3 and get 1.

Step 4: We'll start by adding the digits 2 & 3 in column 4 and get 5.

So, 2007 + 3131 = 5138.

