Let's get this math done. We have 1121 and 7503 and we're going to add them all together.

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

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

Step 3: We'll start by adding the digits 1 & 5 in column 3 and get 6.

Step 4: We'll start by adding the digits 1 & 7 in column 4 and get 8.

So, 1121 + 7503 = 8624.

