Centuries on Sunday

[Home]   [Puzzles & Projects]    [Delphi Techniques]   [Math topics]   [Library]   [Utilities]

 

Search

Search WWW

Search DelphiForFun.org

As of October, 2016, Embarcadero is offering a free release of Delphi (Delphi 10.1 Berlin Starter Edition ).     There are a few restrictions, but it is a welcome step toward making more programmers aware of the joys of Delphi.  They do say "Offer may be withdrawn at any time", so don't delay if you want to check it out.  Please use the feedback link to let me know if the link stops working.

 

Support DFF - Shop

 If you shop at Amazon anyway,  consider using this link. 

     

We receive a few cents from each purchase.  Thanks

 


Support DFF - Donate

 If you benefit from the website,  in terms of knowledge, entertainment value, or something otherwise useful, consider making a donation via PayPal  to help defray the costs.  (No PayPal account necessary to donate via credit card.)  Transaction is secure.

Mensa Daily Puzzlers

For over 15 years Mensa Page-A-Day calendars have provided several puzzles a year for my programming pleasure.  Coding "solvers" is most fun, but many programs also allow user solving, convenient for "fill in the blanks" type.  Below are Amazon  links to the two most recent years.

Mensa 365 Puzzlers  Calendar 2017

Mensa 365 Puzzlers Calendar 2018

(Hint: If you can wait, current year calendars are usually on sale in January.)

Contact

Feedback:  Send an e-mail with your comments about this program (or anything else).

Search DelphiForFun.org only

 

 

 

Centuries That Start on Sunday

Problem Description

I can't remember where I ran across this one,  but the problem is to calculate the probability that a century begins on a Sunday.   

Background and techniques

The attached program calculates and prints the day of week for January 1sts for centuries between 1500 and 4500 AD.  The problem assumes the Gregorian calendar, the one we use today implemented by Pope Gregory in 1584.    When you see the results, the problem will switch from the probability of Sundays to explaining the results you observe.   The source code has extensive comments explaining things,  but I encourage you to run the program and  think about it  first.  

Exploring the Program 

bulletDownload source
bulletDownload  executable

Suggestions for Further Study

If the leap year rules are correct we should be able to calculate the true number of hours per day quite accurately, maybe within 1 day per 400 years?    
 
  [Feedback]   [Newsletters (subscribe/view)] [About me]
Copyright 2000-2017, Gary Darby    All rights reserved.