OK, let's do this. We've got 3815 and 4348 and we're adding them all together.

Step 1: We'll start by adding the digits 5 & 8 in column 1 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 1 & 4 in column 2 and get 6.

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

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

So, 3815 + 4348 = 8163.

