circa 1980 Casio with clock, similar to fx-8100

[grsbanks]

(12-12-2018 11:24 AM)xerxes Wrote:  In such a case, I use the workaround of year-28 to have the correct weekday.

NB: that trick doesn't work unless every year in the interval that's a multiple of 4 is a leap year.

The latest turn of the century was 2000, which was a leap year (multiple of 400) but 1900 was not and 2100 won't be!