Here we go! We're going to add 1035 and 1504 together.

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 3 & 0 in column 2 and get 3.

Step 3: We'll start by adding the digits 0 & 5 in column 3 and get 5.

Step 4: We'll start by adding the digits 1 & 1 in column 4 and get 2.

So, 1035 + 1504 = 2539.

