We have numbers 1000 and 7889. Let's start adding them together.

Step 1: We'll start by adding the digits 0 & 9 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 & 8 in column 3 and get 8.

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

So, 1000 + 7889 = 8889.

