This is what it looks like - it's absolutely FREE so please, fill your boots!
You'll need Microsoft Excel or Libre Office (FREE) to open this file. It will be emailed to you after you've "checked out"

IMPORTANT NOTICE (a.k.a. "Read This Before You Panic!")
You will need Microsoft Excel, Open Office, Libre Office, or Mac Numbers to open this masterpiece of mathematical wizardry. It was designed for actual computers (yes, those things with keyboards), meaning a PC or Mac desktop/laptop. If you insist on trying it on your mobile phone or tablet, well... best of luck, intrepid explorer. It might work. Or it might cause a black hole. Who knows?
DOWNLOAD RULES OF SURVIVAL
After purchasing, you have 30 days to download this calculator. That’s a whole month – more than enough time to locate the big button that says “Download.”
SUPER ULTRA MEGA IMPORTANT WARNING
After downloading, MAKE A BACKUP COPY! I repeat: MAKE A BACKUP COPY! Put it somewhere safe on your machine, on the cloud, on a USB drive, tattoo it onto your arm if necessary—just don't lose it.
Because here’s the thing: I am not your digital babysitter.
- If your PC crashes,
- If your Mac is stolen by rogue squirrels,
- If you "forgot to download it" for 2 years,
…please do not expect me to hand you a fresh copy like some magical download fairy. No take-backs. No do-overs.
SYSTEM REQUIREMENTS
- Requires Microsoft Excel or Open Office.
- Requires a functioning brain to follow the instructions.
Enjoy responsibly.