Let's break this down. We're going to add 2120 and 5411 together.

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

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

Step 3: We'll start by adding the digits 1 & 4 in column 3 and get 5.

Step 4: We'll start by adding the digits 2 & 5 in column 4 and get 7.

So, 2120 + 5411 = 7531.

