We've got two numbers: 8001 and 2004. Let's find their sum.

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

Step 2: We'll start by adding the digits 0 & 0 in column 2 and get 0.

Step 3: We'll start by adding the digits 0 & 0 in column 3 and get 0.

Step 4: We'll start by adding the digits 8 & 2 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 8001 + 2004 = 10005.

