Questions tagged [calendar-computations]
This tag is for questions about combinatorial and computational issues with regards to calendar systems. A typical, well-known mathematical result in this direction is John Conway's Doomsday Algorithm for computing the "day of the week" associated to a given date.
133
questions
2
votes
5
answers
639
views
Prove That the Shortest Period of the Gregorian Calendar is 400 Years
I ask for help.
I would like to resolve the following question:
Let $A$ be the set of natural numbers greater than 1582.
If, for every $Y\in A$ , the years $Y$ and $Y + n$ (of the actual calendar, ...
- 4,260
0
votes
1
answer
2k
views
Difference between two dates in math formula
Good evening guys, I have little problem, I have to calculate how many days do I have between two dates which contains specific day, month and even year, do you guys have any idea how should I do that?...
- 11
2
votes
2
answers
75
views
How can I find the day of the week which an event happened after some time has elapsed?
The problem is as follows:
An astronomer discovers a new comet while scouting the skies on Monday
but decides to report his discovery $256$ days after. What day of the
week did the astronomer ...
- 4,185
4
votes
1
answer
611
views
Math behind leap year cycle
Everybody knows that leap year is year which is divisible by 4. In case of century years, it has to be divisible by 400.
The leap year cycle has 400 years (calendar repeat with the same day-date ...
0
votes
1
answer
142
views
Tonalpohualli calculations
I was doing some math on the Tonalpohualli, the mexica ritual calendar. This calendar has 260 days divided in 13-days periods associated with 20 distinct symbols. Every 13-days period is called a ...
- 276
1
vote
1
answer
1k
views
Formula to find the date given a specific year, month, and day of the week
I need a formula to get me to the first or third specified day of the week of the following year.
So, here is the information I am presented. I have a year (y), a month (m) and a day of the week (n). ...
- 113
2
votes
2
answers
216
views
Identical calendars
We can see, for example, that the years 2009 and 2015 have identical calendars. Similarly, 2000 and 2028.
I read once that given any year X at most 28 years later there will be another year Y, with ...
- 4,260
0
votes
0
answers
467
views
Calculating which day of the week a date falls on using Gauss's algorithm and modulo arithmetic
I've been told there's a straightforward way to determine which day of the week a date falls on, by first using Gauss's algorithm, to find the day of the week of 1st of January. Then this can be ...
- 890
0
votes
2
answers
354
views
I am a twin who celebrated my 13th birthday on Friday the 13th. Is this rare? What is the probability of this occurring?
I was born a twin who celebrated my 13th birthday on Friday the 13th many years ago. Is this rare? What is the probability of this occurring? I am a senior who finally wants to know the answer. ...
0
votes
2
answers
34
views
How do you figure out what # of 4 a Week # is?
If we round down the number of weeks in a year to 52,
And we label each of the 52 weeks either 1, 2, 3, or 4
And we label them in order, the first week of the year being 1, the second being 2, third ...
- 301
0
votes
2
answers
321
views
Number of Tuesdays in five consecutive calendar years taken together is exactly 260. Which day of the week was 1st Jan. of the first of five years?
Number of Tuesdays in five consecutive calendar years taken together is exactly 260. Which day of the week was 1st January of the first of these five years?
I don't know at all how to do this ...
- 571
0
votes
1
answer
113
views
Finding the initial day of the week (Calendars)
Number of Tuesdays in five consecutive calendar years taken together is exactly $260$. Which day of the week was $1st$ January of the first of these five years?
On the basis of given information the ...
- 571
0
votes
1
answer
64
views
Mathematical measure of whether something's on schedule or not?
Say I decide to jog everyday for 1 km. I start jogging and I keep a log of which days I'm jogging on. Now after a couple of months, I notice in my logbook that although I jogged for 1 km on most days, ...
- 348
1
vote
2
answers
10k
views
Monday falls on 20th March, 1995. What was the day on 3rd November, 1994?
Monday falls on 20th March, 1995. What was the day on 3rd November, 1994?
Days in November 1994( starting from 3rd)= $27$
Days in December 1994=$31$
Days in January 1995=$31$
Days in February 1995= $...
- 137
1
vote
4
answers
111
views
If I wanted to determine today's date based on my birthdate, how could I do that mathematically?
Let's say for example my birthday is August 17, 1996. Each year has 365 days except leap years. If I didn't know whether 1996 was a leap year or not, is there a way I can see how many days I've been ...
- 402