Monday, February 22, 2010

Project Euler

My colleague from the computer science department at Contra Costa College, Tom Murphy, thought I might enjoy some more math problems, and pointed me to Project Euler. Here's their intro:
Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.
My programming skills are a bit rusty, so I'm starting with purely mathematical problems. The first one I did is:
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.
[I asked for the problems to be listed in ascending order of difficulty, and this one came up first.]

I figured it out, and used my calculator to do a simple multiplication and addition problem at the end. The 'forum' discussing this problem had lots and lots of programs listed. I was shocked people would ask a computer to solve this one.

I decided to do one a day. This morning I checked the next two and figured I'd at least want to use Excel on them, although I bet there's an elegant way to solve each of them without it. The fourth problem was once again simple enough to solve in a minute, with my trusty TI-83 doing my multiplication.

It looks like a nice set of problems to challenge students with. Thanks, Tom.


  1. Sue,
    Thanks, I was just looking for some material to stimulate a couple of independent study students who are into (guess what) math and programming... sounds like my kind of source.

  2. You're welcome, Pat. Glad I could return the favor in a small way. (You have given us all so many great resources...)

  3. When you get to Euler problem 36, check out my article (of course only after you try it yourself first.)

  4. I've played with Project Euler for a long time. Lots of the problems take lots of thought, though.

  5. Project Euler is amazing and I agree with you -- many of the problems can be solved without a fancy program in Python, C#, or whatever the flavor of the week is.

    FWIW, A middle school computer programming class of mine solved about 20 Euler problems using little more than Excel. (I wrote about it at

    If you want less computer-y but a similar flavor, I liked _Thinking Mathematically_ by John Mason.

  6. Hmm, i might have a copy of that book (but I haven't used it). The cover looks familiar.

    Thanks for the mention. I'll look for it next time I'm at my office. (I'm on sabbatical for the year.)

    I just did my 3rd problem. I had to use Excel on this one (sum of all the even Fibonacci numbers under 4 million), but it was way quick. I didn't even do a formula for even, since there were only about 10 numbers. I just copied them over to another column by hand, and summed.


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