We have numbers 631 and 2758. Let's start adding them together.

Step 1: We'll start by adding the digits 1 & 8 in column 1 and get 9.

Step 2: We'll start by adding the digits 3 & 5 in column 2 and get 8.

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

Step 4: We'll start by adding the digits 0 & 2 in column 4 and get 3.

So, 631 + 2758 = 3389.

