Okay, we are tasked with adding 1631 and 9004. Let's begin!

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

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 6 & 0 in column 3 and get 6.

Step 4: We'll start by adding the digits 1 & 9 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 1631 + 9004 = 10635.

