Project Euler Forum

Try other intervals: 1.1.1905 - 31.12.2004, 1.1.1925 - 31.12.2024 ...
These are 100 years long and 2000 was a leap year, so they are similar to the problem.

If you have entered your old solution you can look at the private forum, that might answer your question.

Not really a big problem, but the bolded part feels a bit weird to me.

You are given the following information, but you may prefer to do some research for yourself.

1 Jan 1900 was a Monday.
Thirty days has September,
April, June and November.
All the rest have thirty-one,
Saving February alone,

Edit: After googling, I just realise it's a way for people to remember how many day are in each months.