OK, let's do this. We've got 2015 and 6883 and we're adding them all together.

Step 1: We'll start by adding the digits 5 & 3 in column 1 and get 8.

Step 2: We'll start by adding the digits 1 & 8 in column 2 and get 9.

Step 3: We'll start by adding the digits 0 & 8 in column 3 and get 8.

Step 4: We'll start by adding the digits 2 & 6 in column 4 and get 8.

So, 2015 + 6883 = 8898.

