We are presented with 6230 and 1255. Let's work out the sum.

Step 1: We'll start by adding the digits 0 & 5 in column 1 and get 5.

Step 2: We'll start by adding the digits 3 & 5 in column 2 and get 8.

Step 3: We'll start by adding the digits 2 & 2 in column 3 and get 4.

Step 4: We'll start by adding the digits 6 & 1 in column 4 and get 7.

So, 6230 + 1255 = 7485.

