Adding Floating-Point Decimals for Fun and Profit is a Developer Tools product. You can open it on Web App, Website. Try Me Out surfaced it because Spotted on Hacker News front page — likely new launch.

The publisher’s own notes say: Many people know that you shouldn’t do decimal calculations, such as those involving U.S. dollars and cents, with the floating-point numbers in most programming languages. This is because decimal numbers can’t be expressed exactly as such floating-point numbers, so you will encounter rounding errors. Famously, with IEEE double-precision floats, 0.1 + 0.2 is not 0.3, but rather, 0.30000000000000004. On the other hand, I use a Python REPL to add up decimal numbers for receipts all the time. Of course, my stakes are lower; I’m summing things in the $1–$100 range and know to manually round the mic

People look at Developer Tools when they want a tool in that category to do a real task, not to collect another login. Use Adding Floating-Point Decimals for Fun and Profit only if the official description matches the job you have this week.

Adding Floating-Point Decimals for Fun and Profit is listed as free to download or try. A free app can still sell extras inside the product, so confirm the current plan on the official page before you rely on it.