We have numbers 877 and 6002. Let's start adding them together.

Step 1: We'll start by adding the digits 7 & 2 in column 1 and get 9.

Step 2: We'll start by adding the digits 7 & 0 in column 2 and get 7.

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

Step 4: We'll start by adding the digits 0 & 6 in column 4 and get 6.

So, 877 + 6002 = 6879.

