We've got two numbers: 1100 and 8215. Let's find their sum.

Step 1: We'll start by adding the digits 0 & 5 in column 1 and get 5.

Step 2: We'll start by adding the digits 0 & 1 in column 2 and get 1.

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

Step 4: We'll start by adding the digits 1 & 8 in column 4 and get 9.

So, 1100 + 8215 = 9315.

