Not to worry, we've got 7789 and 1000. Let's get to adding them!

Step 1: We'll start by adding the digits 9 & 0 in column 1 and get 9.

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

Step 3: We'll start by adding the digits 7 & 0 in column 3 and get 7.

Step 4: We'll start by adding the digits 7 & 1 in column 4 and get 8.

So, 7789 + 1000 = 8789.

