Let's break this down. We're going to add 2172 and 4156 together.

Step 1: We'll start by adding the digits 2 & 6 in column 1 and get 8.

Step 2: We'll start by adding the digits 7 & 5 in column 2 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 1 & 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, 2172 + 4156 = 6328.

