OK, let's do this. We've got 4521 and 264 and we're adding them all together.

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

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

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 4 & 0 in column 4 and get 4.

So, 4521 + 264 = 4785.

