Okay, we are given 1103 and 2406. Let's add them up step by step.

Step 1: We'll start by adding the digits 3 & 6 in column 1 and get 9.

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

Step 3: We'll start by adding the digits 1 & 4 in column 3 and get 5.

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

So, 1103 + 2406 = 3509.

