Let's solve this addition problem. We have 3610 and 2021, and we need to add them 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 1 & 2 in column 2 and get 3.

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 3 & 2 in column 4 and get 5.

So, 3610 + 2021 = 5631.

