Here we go! We're going to add 3503 and 2406 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 5 & 4 in column 3 and get 9.

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

So, 3503 + 2406 = 5909.

