We've got two numbers: 3115 and 5684. Let's find their sum.

Step 1: We'll start by adding the digits 5 & 4 in column 1 and get 9.

Step 2: We'll start by adding the digits 1 & 8 in column 2 and get 9.

Step 3: We'll start by adding the digits 1 & 6 in column 3 and get 7.

Step 4: We'll start by adding the digits 3 & 5 in column 4 and get 8.

So, 3115 + 5684 = 8799.

