Let's solve this addition problem. We have 8111 and 9105, and we need to add them together.

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 1 & 0 in column 2 and get 1.

Step 3: We'll start by adding the digits 1 & 1 in column 3 and get 2.

Step 4: We'll start by adding the digits 8 & 9 in column 4 and get 17.
We'll write down the last digit 7 and carry the 1 to the next column.

So, 8111 + 9105 = 17216.

