Let's solve this addition problem. We have 8503 and 51, and we need to add them together.

Step 1: We'll start by adding the digits 3 & 1 in column 1 and get 4.

Step 2: We'll start by adding the digits 0 & 5 in column 2 and get 5.

Step 3: We'll start by adding the digits 5 & 0 in column 3 and get 5.

Step 4: We'll start by adding the digits 8 & 0 in column 4 and get 8.

So, 8503 + 51 = 8554.

