No problem, let's work through this together. We're starting with 298 and 420 and adding them all up.

Step 1: We'll start by adding the digits 8 & 0 in column 1 and get 8.

Step 2: We'll start by adding the digits 9 & 2 in column 2 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 2 & 4 in column 3 and get 7.

So, 298 + 420 = 718.

