Julian Day CalculatorDate: 05/18/2003 at 10:20:51 From: Tom Subject: Calculating elapsed number of days What is the equation for calculating the elapsed number of days? For example, if I want to know my exact age in days without counting out the days, what would be the equation? Date: 05/18/2003 at 10:32:18 From: Doctor Jerry Subject: Re: Calculating elapsed number of days Hi Tom, Thanks for writing to Ask Dr Math. Suppose you were born in 1991, say on June 1. So, you have the number of days in 1991 plus the days in 1992, 1993, ..., 2002, and then the number of days in 2003 up until today (May 18). We have to remember leap years. 1991: not a leap year; add up the days for June, July,...,December; this would be 30+31+31+30+31+30+31. 1992: leap year; 366 days and so on. 2003: not a leap year; add up January,...,April, and then part of May. There's an entirely different way, but it's somewhat more difficult. You can look up the idea of Julian Day in astronomy. Any date can be given a Julian Day. So, all you have to do is to look up the Julian Day numbers for your birth date and today's date and subtract. Then you would need to add 1. (You need to add one because if the Julian Days were 7,8,9,10, and 11, then there are five days, but 11-7=4. Here's a Web page for a Julian Day calculator. JD Calculator - Walter MacDonald http://www.starlightccd.com/walter/bytebook/javascript/jdcalc.htm - Doctor Jerry, The Math Forum http://mathforum.org/dr.math/ |
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