No problem, let's work through this together. We're starting with 6851 and 1148 and adding them all up.

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

Step 2: We'll start by adding the digits 5 & 4 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 6 & 1 in column 4 and get 7.

So, 6851 + 1148 = 7999.

