No problem, let's work through this together. We're starting with 1518 and 5260 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 1 & 6 in column 2 and get 7.

Step 3: We'll start by adding the digits 5 & 2 in column 3 and get 7.

Step 4: We'll start by adding the digits 1 & 5 in column 4 and get 6.

So, 1518 + 5260 = 6778.

