OK, let's do this. We've got 6450 and 1418 and we're adding them all together.

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

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 4 & 4 in column 3 and get 8.

Step 4: We'll start by adding the digits 6 & 1 in column 4 and get 7.

So, 6450 + 1418 = 7868.

