Let's break this down. We're going to add 100 and 9051 together.

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

Step 2: We'll start by adding the digits 0 & 5 in column 2 and get 5.

Step 3: We'll start by adding the digits 1 & 0 in column 3 and get 1.

Step 4: We'll start by adding the digits 0 & 9 in column 4 and get 9.

So, 100 + 9051 = 9151.

