We have numbers 3103 and 4015. Let's start adding them together.

Step 1: We'll start by adding the digits 3 & 5 in column 1 and get 8.

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 & 0 in column 3 and get 1.

Step 4: We'll start by adding the digits 3 & 4 in column 4 and get 7.

So, 3103 + 4015 = 7118.

