We are presented with 503 and 7226. Let's work out the sum.

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 & 2 in column 2 and get 2.

Step 3: We'll start by adding the digits 5 & 2 in column 3 and get 7.

Step 4: We'll start by adding the digits 0 & 7 in column 4 and get 7.

So, 503 + 7226 = 7729.

