Let's solve this addition problem. We have 2603 and 1260, and we need to add them together.

Step 1: We'll start by adding the digits 3 & 0 in column 1 and get 3.

Step 2: We'll start by adding the digits 0 & 6 in column 2 and get 6.

Step 3: We'll start by adding the digits 6 & 2 in column 3 and get 8.

Step 4: We'll start by adding the digits 2 & 1 in column 4 and get 3.

So, 2603 + 1260 = 3863.

