No problem, let's work through this together. We're starting with 5661 and 3156 and adding them all up.

Step 1: We'll start by adding the digits 1 & 6 in column 1 and get 7.

Step 2: We'll start by adding the digits 6 & 5 in column 2 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 6 & 1 in column 3 and get 8.

Step 4: We'll start by adding the digits 5 & 3 in column 4 and get 8.

So, 5661 + 3156 = 8817.

