Okay, we are tasked with adding 6216 and 9128. Let's begin!

Step 1: We'll start by adding the digits 6 & 8 in column 1 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 1 & 2 in column 2 and get 4.

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 6 & 9 in column 4 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

So, 6216 + 9128 = 15344.

