OK, let's do this. We've got 253 and 113 and we're adding them all together.

Step 1: We'll start by adding the digits 3 & 3 in column 1 and get 6.

Step 2: We'll start by adding the digits 5 & 1 in column 2 and get 6.

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

So, 253 + 113 = 366.

