Sunday, April 9, 2017

calendar - How Do I Know If it's a Hebrew Leap Year?


How can I tell if a given year is a Hebrew Leap Year? The simpler, the better.



[Assuming we are using a fixed calendar, not like the "olden days".]



Answer



If you have a piano keyboard handy, you can use it as a mnemonic aid:


              Y mod 19 =

│ ▐██▌ ▐██▌ │ ▐██▌ ▐██▌ ▐██▌ │
│ ▐██▌ ▐██▌ │ ▐██▌ ▐██▌ ▐██▌ │
│ ▐██▌ ▐██▌ │ ▐██▌ ▐██▌ ▐██▌ │
│ ▐██▌ ▐██▌ │ ▐██▌ ▐██▌ ▐██▌ │
│ ▐██▌ ▐██▌ │ ▐██▌ ▐██▌ ▐██▌ │

│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
│ 0 │ 3 │ 6 │ 8 │ 11 │ 14 │ 17 │
└────┴────┴────┴────┴─────┴────┴────┘


  • half step between white keys (no intervening black key) = leap years 2 years apart

  • whole step between white keys (black key between them) = leap years 3 years apart


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