No problem, let's work through this together. We're starting with 2355 and 3502 and adding them all up.

Step 1: We'll start by adding the digits 5 & 2 in column 1 and get 7.

Step 2: We'll start by adding the digits 5 & 0 in column 2 and get 5.

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 2 & 3 in column 4 and get 5.

So, 2355 + 3502 = 5857.

