OK, let's do this. We've got 2118 and 640 and we're adding them all together.

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 1 & 4 in column 2 and get 5.

Step 3: We'll start by adding the digits 1 & 6 in column 3 and get 7.

Step 4: We'll start by adding the digits 2 & 0 in column 4 and get 2.

So, 2118 + 640 = 2758.

