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When this calculator hits 88 miles an hour...

A Casio calculator, the moment it achieves time displacement.
A Casio calculator, the moment it achieves time displacement.

Great Scott! Step back in time 40 years from today, and the cult hit Back to the Future would have been hitting theaters worldwide on July 3, 1985. Coincidentally, this was the same year that Casio released the world's first commercially available graphing calculator, the fx-7000G, ushering a new era of personal computing and revolutionizing math education.


This year, Casio celebrates its own 40th anniversary of the graphing calculator with the release of the new fx-CG100 ClassWiz Color Graph, which raises the bar on accessibility and user-friendliness, while maintaining the same computational accuracy of previous iterations. Casio is also celebrating its 60th anniversary of desktop computation from the inception of the "001" calculator.


Casio has come a long way, but frankly, we have a further way to go before we build our first time machine. While we may not have flux capacitors or batteries that generate 1.21 gigawatts (that would be simply too much power for a calculator!), I've created something that would make Doc Brown proud: a date and time Python program that runs on the Casio Grapher OS.


Written in MicroPython with no library dependencies, the program handles two main computations that I find myself needing constantly in my time machine:

  1. Time arithmetic: Add or subtract hours, minutes, and seconds to any given time in 12-hour format, accounting for AM/PM.

  2. Date calculations: Add or subtract any number of days to a date, accounting for different month lengths and leap year handling.


calculator emulator depicting time and date computation
Screenshots of the program using the free emulator on Classpad.net (U.S. Only)

Download the program:


The program is built around a simple but powerful concept: converting everything to a common unit and then converting back. For time calculations, everything gets converted to seconds. When you input a time like 2:30:45 PM plus 1 hour 36 seconds, the program:


  1. Converts your 12-hour input to 24-hour format (2:30 PM becomes 14:30)

  2. Turns everything into seconds: (14×3600) + (30×60) + 45 = 52,245 seconds

  3. Adds your change: 52,245 + 3,636 = 55,881 seconds

  4. Converts back: 55,881 seconds = 15 hours, 31 minutes, 21 seconds

  5. Formats it nicely: 3:31:21 PM


The date calculations work similarly but with a bit more complexity to handle the varying lengths of months and leap years.


How to install and run on the calculator:

  1. Download the zip file above containing the Python program, and extract the file.

  2. Connect your Casio graphing calculator to your computer (Mini-USB for older models, USB-C for the fx-CG100)

  3. Drag and drop the Python program into your /@MainMem/ folder.

  4. Go to the Python app. On older models, press [F1] (Run) while timecalc.py is highlighted. On the fx-CG100, press [TOOLS], [2] (File), [2] (Open), and select timecalc.py. Then select [TOOL], [4] (Run).


Happy calculating!

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