Okay, we are tasked with adding 5845 and 1020. 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 4 & 2 in column 2 and get 6.

Step 3: We'll start by adding the digits 8 & 0 in column 3 and get 8.

Step 4: We'll start by adding the digits 5 & 1 in column 4 and get 6.

So, 5845 + 1020 = 6865.

