OK, let's do this. We've got 1004 and 4085 and we're adding them all together.

Step 1: We'll start by adding the digits 4 & 5 in column 1 and get 9.

Step 2: We'll start by adding the digits 0 & 8 in column 2 and get 8.

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

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

So, 1004 + 4085 = 5089.

