Okay, we are tasked with adding 2001 and 2070. Let's begin!

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

Step 2: We'll start by adding the digits 0 & 7 in column 2 and get 7.

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 2 & 2 in column 4 and get 4.

So, 2001 + 2070 = 4071.

