Let's solve this addition problem. We have 8712 and 3333, and we need to add them together.

Step 1: We'll start by adding the digits 2 & 3 in column 1 and get 5.

Step 2: We'll start by adding the digits 1 & 3 in column 2 and get 4.

Step 3: We'll start by adding the digits 7 & 3 in column 3 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 8 & 3 in column 4 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 8712 + 3333 = 12045.

