We have numbers 420 and 546. Let's start adding them together.

Step 1: We'll start by adding the digits 0 & 6 in column 1 and get 6.

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 4 & 5 in column 3 and get 9.

So, 420 + 546 = 966.

