Let's get this math done. We have 6842 and 3135 and we're going to add them all together.

Step 1: We'll start by adding the digits 2 & 5 in column 1 and get 7.

Step 2: We'll start by adding the digits 4 & 3 in column 2 and get 7.

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

Step 4: We'll start by adding the digits 6 & 3 in column 4 and get 9.

So, 6842 + 3135 = 9977.

