Okay, we are given 1187 and 3406. Let's add them up step by step.

Step 1: We'll start by adding the digits 7 & 6 in column 1 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 8 & 0 in column 2 and get 9.

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 & 3 in column 4 and get 4.

So, 1187 + 3406 = 4593.

