Okay, we are tasked with adding 2221 and 4170. Let's begin!

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

Step 2: We'll start by adding the digits 2 & 7 in column 2 and get 9.

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

Step 4: We'll start by adding the digits 2 & 4 in column 4 and get 6.

So, 2221 + 4170 = 6391.

