We are presented with 1220 and 2725. 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 2 & 2 in column 2 and get 4.

Step 3: We'll start by adding the digits 2 & 7 in column 3 and get 9.

Step 4: We'll start by adding the digits 1 & 2 in column 4 and get 3.

So, 1220 + 2725 = 3945.

