Do you hate the guys in your company’s finance department? Are they always making it a pain in the ass for you to get your invoices paid, or make purchases? Here’s your chance to get sweet, sweet revenge.

Simply replace the entire department’s regular desk calculators with one of these “special” calculators, guaranteed to miscalculate everything they key into them. To seal the deal, you might want to attach a company memo stating they they’ve all received their new calculators as a gift from the company.

The Wrongulator may look like a typical solar LCD calculator, but it’s designed to drive its users batty, by replacing all proper mathematical logic with complete and utter rubbish, providing brilliant answers like “10 + 5 = 10”.

You can get your hands on one over at UK gadget shop RED5 for £4.95 (~$7 USD). Just be sure not to let one accidentally get into the hands of the payroll department.