We are presented with 8113 and 3765. Let's work out the sum.

Step 1: We'll start by adding the digits 3 & 5 in column 1 and get 8.

Step 2: We'll start by adding the digits 1 & 6 in column 2 and get 7.

Step 3: We'll start by adding the digits 1 & 7 in column 3 and get 8.

Step 4: We'll start by adding the digits 8 & 3 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 8113 + 3765 = 11878.

