Ready to do some math? We're starting with 121 and 9001 and adding them up.

Step 1: We'll start by adding the digits 1 & 1 in column 1 and get 2.

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

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 & 9 in column 4 and get 9.

So, 121 + 9001 = 9122.

