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day_of_week [2017.11.14 15:46] – Steve Isenbergday_of_week [2020.12.29 06:25] – Steve Isenberg
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 +~~NOCACHE~~
 =====Doomsday algorithm===== =====Doomsday algorithm=====
 Given a date, determine the day of the week it falls on.  All based on last day of February in the year, the doomsday.  Several places have info from which I've put this together for the Lexington Computer Group; see [[https://en.wikipedia.org/wiki/Doomsday_rule|Wikipedia]]'s entry.\\ Given a date, determine the day of the week it falls on.  All based on last day of February in the year, the doomsday.  Several places have info from which I've put this together for the Lexington Computer Group; see [[https://en.wikipedia.org/wiki/Doomsday_rule|Wikipedia]]'s entry.\\
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 18 is even, /2 is 9, 9 is odd +11 is 20. Mod 7 is 6, from 7 is 1, so doomsday for 1918 is Thursday\\ 18 is even, /2 is 9, 9 is odd +11 is 20. Mod 7 is 6, from 7 is 1, so doomsday for 1918 is Thursday\\
 Nov 7 is Thursday, so 11th is Monday. Nov 7 is Thursday, so 11th is Monday.
 +
 +=====Convert Fahrenheit to Centigrade and Back In Your Head=====
 +As a shortcut, F=degrees Fahrenheit and C=degrees Centigrade (or Celsius).\\ 
 +The basic conversion is exact:\\ Degrees F = (Degrees C * 9/5) + 32 and\\ Degrees C = (Degrees F - 32) * 5/9
 +
 +===F to C===
 +  - Subtract 32 from F
 +  - Halve the result
 +  - Add back 10% of the result
 +  - Done, you have C.
 +
 +Example\\ 
 +Start: F = 57\\ 
 +Minus 32: F-32 = 25\\ 
 +Halve it: 25/2 = 12.5\\ 
 +Add back 1/10: 12.5 + 1.3 = 13.8 or 14C
 +
 +===C to F===
 +  - Double C
 +  - Double the result
 +  - Subtract 1/10 of the result
 +  - Add 32
 +  - Done, you have F.
 +
 +Example\\ 
 +Start: C=32\\ 
 +Double it: C*2 = 64\\ 
 +Subtract 1/10: 64-6 = 58\\ 
 +Add 32: 58+32 = 90F|
 +
 +
 +
 +====try====
 +|===F to C===\\ 
 +  - Subtract 32 from F\\ 
 +  - Halve the result\\ 
 +  - Add back 10% of the result\\ 
 +  - Done, you have C.\\ 
 +\\ 
 +Example\\ 
 +Start: F = 57\\ 
 +Minus 32: F-32 = 25\\ 
 +Halve it: 25/2 = 12.5\\ 
 +Add back 1/10: 12.5 + 1.3 = 13.8 or 14C|\\ 
 +\\ 
 +===C to F===\\ 
 +  - Double C\\ 
 +  - Double the result\\ 
 +  - Subtract 1/10 of the result\\ 
 +  - Add 32\\ 
 +  - Done, you have F.\\ 
 +\\ 
 +Example\\ 
 +Start: C=32\\ 
 +Double it: C*2 = 64\\ 
 +Subtract 1/10: 64-6 = 58\\ 
 +Add 32: 58+32 = 90F|
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day_of_week.txt · Last modified: 2022.11.12 13:06 by Steve Isenberg