Here we go! We're going to add 2103 and 3606 together.

Step 1: We'll start by adding the digits 3 & 6 in column 1 and get 9.

Step 2: We'll start by adding the digits 0 & 0 in column 2 and get 0.

Step 3: We'll start by adding the digits 1 & 6 in column 3 and get 7.

Step 4: We'll start by adding the digits 2 & 3 in column 4 and get 5.

So, 2103 + 3606 = 5709.

