We are presented with 5638 and 7003. Let's work out the sum.

Step 1: We'll start by adding the digits 8 & 3 in column 1 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

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

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 5 & 7 in column 4 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 5638 + 7003 = 12641.

