Okay, we are tasked with adding 9120 and 8156. Let's begin!

Step 1: We'll start by adding the digits 0 & 6 in column 1 and get 6.

Step 2: We'll start by adding the digits 2 & 5 in column 2 and get 7.

Step 3: We'll start by adding the digits 1 & 1 in column 3 and get 2.

Step 4: We'll start by adding the digits 9 & 8 in column 4 and get 17.
We'll write down the last digit 7 and carry the 1 to the next column.

So, 9120 + 8156 = 17276.

