Hello, everyone, Another dumb question: does the TMG date calculator tool (or others) take into consideration leap years and the month of February?? Distant cousin-in-law died 15 Apr 1864 (a leap year), aged 50-1-24. Date calculator calculates his birth date as 22 Feb 1814, but that seemed wrong to me--even assuming 28 days for Feb., then based on 22 Feb to 15 Mar, well, that's just 21 days, not 24; throwing in the leap year, well, then that's 22 days. So ... seems to me he was probably born 20 Feb 1814, that is, 9 days in Feb. plus 15 days in March equals 24 (March) and adding one month, brings us/me to Apr 24 Am I overthinking this?? (Or hah, showing my poor math skills??) Does anyone know if waaay back then did they even worry about February not being 30 or 31 days, or for that matter leap years? As ever, thanks. Sam

Sam, I think it works from smallest (days) to largest (years) when subtracting dates. First, subtract the days from the given date. You started with 15 April 1864, so subtract 24 days and you get 22 March 1864. Next, subtract a month, that yields 22 February 1864. Last, subtract 50 years, that yields 22 February 1814. John

I've not used the TMG date calculator; in my pre-TMG days, I used MS Outlook's calendar, in a manner something like John describes: Go to date of death. Go back n days. Go back n months. Go back n years. It would be interesting to know how accurate this method is (but not interesting enough for me to test it myself<g>). It would also be interesting to know how the accuracy of this calculation compares to the accuracy of the original calculation (which appear on the gravestone or in contemporary records). I wonder if they didn't do it the same way we're describing here. Rick Van Dusen On 9/22/2015 9:13 AM, John Cardinal via wrote: > Sam, > > I think it works from smallest (days) to largest (years) when subtracting > dates. : : : > John

I wrote an article for NGSQ that touched on this question.* I looked at over 90 texts written in English or German and found that there were 3 methods taught for subtracting one date from another. (Unfortunately, we often have no way of knowing which method was used in a particular case.) And yes, they did worry about how many days were in a given month. 1. borrow the number of days in the month preceding the month in the minuend. A calendar-counting equivalent is to start with the date in the minuend, then count back days, then months, then years. [The same to reverse the calculation using subtraction. Based on my testing, this is the reversal method used by TMG, Roots Magic, and Legacy.] 2. borrow the number of days in the month in the subtrahend. One calendar-counting equivalent is to start with the date in the minuend, then count back years, then months, then days. [To reverse the calculation using subtraction, borrow the number of days in the month in the difference.] 3. always borrow 30. [The same to reverse the calculation using subtraction.] 4. Another method that I did not see in the arithmetic texts but which is theoretically possible is to borrow the number of days in the month given in the minuend. There is no sensible calendar-counting equivalent. [The same to reverse the calculation using subtraction.] If borrowing was involved in the original calculation, then you usually don't know which method was used for the original calculation. So, to subtract an interval/age from a date one should use all methods [in square brackets above] to reverse the calculation and consider all results equally valid. Hope this isn't too much more than you wanted to know :) Barbara * Barbara Levergood. "Calculating and Using Dates and Date Ranges." National Genealogical Society Quarterly 102 (March 2014): 51-75. See especially Table 18. On 9/22/2015 10:25 AM, Blah BlahBlah via wrote: > Hello, everyone, > > Another dumb question: does the TMG date calculator tool (or > others) take into consideration leap years and the month of February?? > > Distant cousin-in-law died 15 Apr 1864 (a leap year), aged 50-1-24. > Date calculator calculates his birth date as 22 Feb 1814, but that > seemed wrong to me--even assuming 28 days for Feb., then based on 22 > Feb to 15 Mar, well, that's just 21 days, not 24; throwing in the leap > year, well, then that's 22 days. So ... seems to me he was probably > born 20 Feb 1814, that is, 9 days in Feb. plus 15 days in March equals > 24 (March) and adding one month, brings us/me to Apr 24 > > Am I overthinking this?? (Or hah, showing my poor math skills??) > Does anyone know if waaay back then did they even worry about February > not being 30 or 31 days, or for that matter leap years? > > As ever, thanks. > > Sam > The TMG archive is found here: http://archiver.rootsweb.ancestry.com/th/index/TMG/ > Instructions on how to subscribe to TMG: http://lists.rootsweb.ancestry.com/index/other/Software/TMG.html > ------------------------------- > To unsubscribe from the list, please send an email to TMG-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message > -- Barbara Levergood levergood@att.net (=^·^=)~