Let's solve this addition problem. We have 8448 and 1451, and we need to add them together.

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

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

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

Step 4: We'll start by adding the digits 8 & 1 in column 4 and get 9.

So, 8448 + 1451 = 9899.

