Okay, we are tasked with adding 8085 and 400. Let's begin!

Step 1: We'll start by adding the digits 5 & 0 in column 1 and get 5.

Step 2: We'll start by adding the digits 8 & 0 in column 2 and get 8.

Step 3: We'll start by adding the digits 0 & 4 in column 3 and get 4.

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

So, 8085 + 400 = 8485.

