We've got two numbers: 154 and 815. Let's find their sum.

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

Step 2: We'll start by adding the digits 5 & 1 in column 2 and get 6.

Step 3: We'll start by adding the digits 1 & 8 in column 3 and get 9.

So, 154 + 815 = 969.

