Let's get this math done. We have 9002 and 3540 and we're going to add them all together.

Step 1: We'll start by adding the digits 2 & 0 in column 1 and get 2.

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

Step 3: We'll start by adding the digits 0 & 5 in column 3 and get 5.

Step 4: We'll start by adding the digits 9 & 3 in column 4 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 9002 + 3540 = 12542.

