Okay, we are given 2621 and 7020. Let's add them up step by step.

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

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

Step 3: We'll start by adding the digits 6 & 0 in column 3 and get 6.

Step 4: We'll start by adding the digits 2 & 7 in column 4 and get 9.

So, 2621 + 7020 = 9641.

