Zeller’s congruence is an algorithm devised by Christian Zeller to calculate the day of the week for any Julian or Gregorian calendar date. Basically, SpeedCalendar requires mental arithmetic to calculate the day of the week. There are several technique to do it.
- Pure calculation
- Finger method
- x1.25 method
- Quotient method
- 28/56/84 method
- Kurukuru method
- Rote memorization method
The summary material (document or youtube) will be disclosed one by one. For the time being, please contact us for Special Lesson below.
These methods can be introduced to you over the Internet (e.g. Zoom, Skype, Teams), as far as the Speed Calendar Commissioner is available.
- Free of charge (treat beer is welcome!)
- English, Chinese and Japanese are acceptable.
- Consideration of time difference is required, commissioner lives in Japan.