Let's solve this addition problem. We have 1863 and 8136, and we need to add them together.

Step 1: We'll start by adding the digits 3 & 6 in column 1 and get 9.

Step 2: We'll start by adding the digits 6 & 3 in column 2 and get 9.

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 1 & 8 in column 4 and get 9.

So, 1863 + 8136 = 9999.

