No problem, let's work through this together. We're starting with 456 and 3402 and adding them all up.

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

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 4 & 4 in column 3 and get 8.

Step 4: We'll start by adding the digits 0 & 3 in column 4 and get 3.

So, 456 + 3402 = 3858.

