Cache update: 1 hour

Proposed Release Schedule for New Problems

  • Problem 666 will be accessible in 1 day, 8 hours, 34 minutes (Saturday, 20th April 2019, 01:00 pm)
  • Problem 667 is scheduled for Saturday, 27th April 2019, 04:00 pm
  • Problem 668 is scheduled for Saturday, 4th May 2019, 07:00 pm
  • Problem 669 is scheduled for Saturday, 11th May 2019, 10:00 pm
  • Problem 670 is scheduled for Sunday, 19th May 2019, 01:00 am
  • Problem 671 is scheduled for Sunday, 19th May 2019, 01:00 am

Recent News

3 March 2019: Style Sheet Update

As technology has evolved it seems that Project Euler has taken time to catch-up. A common request in recent years has been to modify the style sheets to be make the website mobile device friendly. This includes a responsive framework that should dynamically adapt the display to accommodate a variety of screen widths.

It has taken a lot of work, given the regimented tabular structure of many pages, but we are pleased to reveal the fruits of that labour.

This has required significant changes not only to the style sheets, but the way in which the scripts dynamically produce pages. Extensive testing has been made, but as you can imagine there are going to be some setups that had not been anticipated and consequently pages may not render as expected. In addition, as part of the the process a number of decisions have been made to modernise the style sheets, including the use of CSS variables to simplify future changes. Whereas support for this has been in place in all of the main browsers for several years now, it does mean that some old browsers may suffer. Special provision has been made to provide legacy CSS support for Internet Explorer, which means that IE will only render a version of the default theme .

If you notice any specific issues, then we would ask you to report them at the following address on our alternative forum.
https://projecteuler.chat/viewtopic.php?f=5&t=6873

For many members they will notice nothing more than, what we hope, a cleaner more pleasing appearance. For mobile device users we hope that the effort was worth it and navigating the site becomes an enjoyable experience.

20 October 2018: Weekly Publication Schedule

About a year ago we decided to reduce the release of new problems to one problem every two weeks.

Thanks to the many contributions made by our members we now have enough problems in stock to release one problem every week. Because we don't want the authors to wait too long before their problem is published we make the following decision: At the start of each new batch of problems (usually 6 problems) we will make a decision to release those problems weekly if there are sufficient problems in stock; otherwise we will follow a two-weekly schedule for that batch of problems. At the top of news page you can always see when new problems are released.

We hope that members will keep contributing enough proposals to maintain a weekly publication scheme.

25 September 2018: Progress Page Change

Just in case you thought your Progress page was broken, a small and deliberate change has been made to the colour scheme on the grid showing which problems you have solved. Along with being more in-keeping with the general site colour scheme, the shading indicates the relative difficulty of the problems. Hopefully the changes aren't too distracting and will serve to provide more useful information on that page.

27 May 2018: Project Euler and the GDPR

As many of you will know, the law concerning any data held by European citizens: General Data Protection Regulation (GDPR), came into effect on 25 May 2018. Not only is the website hosted in Europe, but a large proportion of our membership also live within Europe, so this legislation affects us.

For some time now we have been reviewing and discussing our policies and practices to ensure that we would be compliant with the new legislation when it came into effect. If you are familiar with the GDPR, then you will know from our previous privacy policy that the main website, projecteuler.net, was already compliant. This is due to a combination of having anonymous accounts (that is, we require no personal data which could be used to identify an individual), members having full control over any data they enter, and always providing a full and transparent disclosure of how we handle data. However, as a way to ensure that we communicate as clearly as possible how we operate it was felt by the team that the privacy policy should be updated to ensure greater clarity in all parts. For this reason, we ask all members to take the time to read and review the Privacy Policy.

Where we have made important changes, however, is with the Project Euler alternative forum: projecteuler.chat, which uses the latest release of the phpBB forum software. In order to operate with consistency across both websites we have made the decision to ensure anonymity there too. That is, we have removed all user email addresses from the database, there is neither a requirement nor an option to enter email addresses, and user IP addresses are no longer recorded. So it should be noted that all previous functionality relating to emails, such as notifications, are no longer available. As with the main website, if you have already created an account at the forum, then we would ask that you visit the website to read and review the privacy policy.

We hope that you are happy with the outcome of our review and continue to enjoy being a part of the Project Euler community.

18 February 2018: Changing Statistical Data View

It is now possible to change the statistical data shown on the Statistics pages from the default view of all registered members to active members only; that is, members who have solved a problem within the last 365 days.

It should also be noted that changing to the alternative view will create a cookie (name = statistics_show) to remember your choice. If you revert back to all registered members, then the cookie will be deleted. The Privacy Policy has been updated to reflect this change.