A calculator inspired by the classic HP-01 calculator watch:

• Performs calculations on four datatypes: numeric, elapsed time, time of day, and date.
• Find the day of the week, add or subtract days from a calendar date.
• Compute percentage, swap inputs, convert an elapsed time to and from decimal time.
• Store any type of value in persistent memory.

The Watch app provides a subset of these features:

• Calculations on all datatypes.
• Percentage and memory storage.