Okay, we are tasked with adding 154 and 8004. Let's begin!

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

Step 2: We'll start by adding the digits 5 & 0 in column 2 and get 5.

Step 3: We'll start by adding the digits 1 & 0 in column 3 and get 1.

Step 4: We'll start by adding the digits 0 & 8 in column 4 and get 8.

So, 154 + 8004 = 8158.

