We've got two numbers: 2013 and 1561. Let's find their sum.

Step 1: We'll start by adding the digits 3 & 1 in column 1 and get 4.

Step 2: We'll start by adding the digits 1 & 6 in column 2 and get 7.

Step 3: We'll start by adding the digits 0 & 5 in column 3 and get 5.

Step 4: We'll start by adding the digits 2 & 1 in column 4 and get 3.

So, 2013 + 1561 = 3574.

