No problem, let's work through this together. We're starting with 3320 and 3541 and adding them all up.

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

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

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

Step 4: We'll start by adding the digits 3 & 3 in column 4 and get 6.

So, 3320 + 3541 = 6861.

