Okay, we are tasked with adding 6638 and 100. Let's begin!

Step 1: We'll start by adding the digits 8 & 0 in column 1 and get 8.

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 & 1 in column 3 and get 7.

Step 4: We'll start by adding the digits 6 & 0 in column 4 and get 6.

So, 6638 + 100 = 6738.

