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Putting Time In Perspective

Calculating Where Events Fall

I     You start knowing that 2 ratios are equal.

# of years ago event took place               # of days from the end of a 365 day year
------------------------------------------      =      ------------------------------------------------------
                     
Scale                                                                          365  

II    You can then solve the equation for the unknown "# of days from the end of a 365 day year".

# of years ago event took place   X   365                                    
-----------------------------------------------------      =   
# of days from the end of a 365 day year
                               
Scale                                

III   Subtract the result in step II from 365 to get the "day" of the year on which the event fell.

365 - # of days from the end of a 365 day year     =    day of year on which event fell

IV    Look up the result from step III in the following table to get the Month. (Find the highest number in the left column that is less than or equal to the "day" from step III. The Month you want is to the right of the number you found in the table.)

            example: 30.9854 would give you January   

            0     January
          31    February
          59    March
          90    April
        120    May
        151    June
        181    July
        212    August
        243    September
        273    October
        304    November
        334    December
        365    December

V    Subtract the number to the left of the Month you found in step IV from the "day" you come up with in step III to get the "day of the month". If your result contains a fraction, add 1 to the integer portion of the result to get the "day of the month".

        example: 30.9854 - 0 = 30.9854                30 + 1 = 31

VI    If the result in step III has no remainder, then the event occurred at 12 am exactly. If there is a remainder, then you can proceed to calculate the "time of day" at which the event occurred using steps VII through IX.

VII   Multiply the decimal portion of the result in step III by 24. The integer portion of this result is the hour of the day. If the integer portion of this result is more than 12, subtract 12 from it to get a PM hour; otherwise you have an AM hour.
(exception: 0 = 12 am and 12 = 12 pm)

         example: .9854 * 24 = 23.6496                 23 - 12 = 11 pm

VIII   To get the minute of the hour, multiply the decimal portion of the result in step VII by 60. The integer portion of this result is the minute of the hour.

         example: .6496 * 60 = 38.94                     38 minutes

IX    To get the # of seconds of the next minute, multiply the decimal portion of the result in step VIII by 60. Drop the decimal portion of your result. The result is the number of whole seconds past the previous whole minute.

        example: .94 * 60 = 56.4                             56 seconds


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original web posting: Wednesday, September 9, 1998
last modified: Tuesday, March 16, 2004