OK, let's do this. We've got 9144 and 640 and we're adding them all together.

Step 1: We'll start by adding the digits 4 & 0 in column 1 and get 4.

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

Step 3: We'll start by adding the digits 1 & 6 in column 3 and get 7.

Step 4: We'll start by adding the digits 9 & 0 in column 4 and get 9.

So, 9144 + 640 = 9784.

