We are presented with 8815 and 4224. Let's work out the sum.

Step 1: We'll start by adding the digits 5 & 4 in column 1 and get 9.

Step 2: We'll start by adding the digits 1 & 2 in column 2 and get 3.

Step 3: We'll start by adding the digits 8 & 2 in column 3 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 8 & 4 in column 4 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

So, 8815 + 4224 = 13039.

