No problem, let's work through this together. We're starting with 1981 and 7935 and adding them all up.

Step 1: We'll start by adding the digits 1 & 5 in column 1 and get 6.

Step 2: We'll start by adding the digits 8 & 3 in column 2 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 9 & 9 in column 3 and get 19.
We'll write down the last digit 9 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 1 & 7 in column 4 and get 9.

So, 1981 + 7935 = 9916.

