TLA Systems has brought is popular calculator app to the Apple Watch today through the latest version of PCalc for iPhone. The PCalc Apple Watch app features a fully functional calculator for quickly crunching numbers from your watch — 1985 Casio-style like the similar Calcbot app — and similarly features a clever tip calculator that makes splitting the bill a cinch.
PCalc for Apple Watch also includes an app Glance that displays the most recent result from PCalc and serves as a shortcut to the calculator app from the watch face. Force Touching in PCalc on Apple Watch brings up a menu that includes a Send to iPhone feature as well.
While Apple includes a calculator app on the iPhone, it does not extend that to the Apple Watch. While it might seem like a throwback to the 80s, discretely calculating your tip and total at dinner has been a slick use of Apple Watch for me so far.