Let's solve this addition problem. We have 8673 and 6823, and we need to add them together.

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

Step 2: We'll start by adding the digits 7 & 2 in column 2 and get 9.

Step 3: We'll start by adding the digits 6 & 8 in column 3 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 8 & 6 in column 4 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

So, 8673 + 6823 = 15496.

