We are presented with 1202 and 5635. Let's work out the sum.

Step 1: We'll start by adding the digits 2 & 5 in column 1 and get 7.

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 2 & 6 in column 3 and get 8.

Step 4: We'll start by adding the digits 1 & 5 in column 4 and get 6.

So, 1202 + 5635 = 6837.

