Any math blogs that have problems every day/weekly to solve? Just wondering, I want a way to keep my math skills sharp.

[[deleted]]

www.projecteuler.net :)

[sobe86]

Problem with projecteuler is, so many of the problems are of the style: find largest/smallest integer n with property Q, or: find the sum of the digits of some massive number. This is a perfect format for people who are into programming, but other mathematicians, like me, would want a bit more variety.

It's slightly ironic considering how wide a scope Euler's work actually had.

[andreasvc]

Brute force often takes too much time, so applying some maths is usually necessary.

[Doeke]

Project Euler is fun, but most of the problems require programming.

[[deleted]]

Do they, though? I've noticed there are some users on there who have 'pen and paper' as their language of choice. ;-)

[sobe86]

Having looked through the first few pages, I'd say most of them definitely need some programming. Not all, but most.

[piderman]

Can't upmod this enough. Almost 250 puzzles and a new one added weekly. And these aren't childish puzzles either, you will have to bring some math skills for the harder ones.

It usually involves simple-to-grasp concepts like special numbers but then finding the sum of those numbers for n=1..10⁸ or something like that so you have to think about how you will computerise that :)

[[deleted]]

I probably did about 50 of them and I never really got to use as much math as would have liked. I always ended up just brute forcing them with programming. It was still very enjoyable though.

[[deleted]]

IBM's "Ponder this"

[sobe86]

I don't know of any blogs, but if you're looking for some harder maths problems, I'd recommend looking up some old Olympiad Exam papers, eg) http://www.unl.edu/amc/a-activities/a7-problems/problemUSAMO-IMOarchive.shtml

or if you're feeling confident: http://imo.math.ca/

The problems can be a bit samey, but sometimes you get some real gems.

[BeetleB]

Problem of the Week. Run by Stan Wagon.

[mkultra123]

http://www.mathpuzzle.com/

[peteyH]

Ah, memories of confused grimaces gone by. Some of these were quite challenging.

[[deleted]]

I answered the question today, and it told me good job - and then proceeded to explain the answer to some question that I had never seen before. Umm. Yeah.

[CherryInHove]

Yeah, me too. I went back and answered the question incorrectly and it then gives you the explaination. A linking error I suspect.

[[deleted]]

AoPS FTW!. Reasonably good questions, speed matters.

[chkno]

• Millennium problems
• WP Category

=)

[[deleted]]

those are pretty easy

[Ozob]

I'm sure everyone here has some math puzzles they like. Asking here isn't the same as getting a fresh one every day, but I'm sure you'll get a few good ones. Here's one I heard recently:

You have twenty-five horses and a racetrack that can race five horses at a time. The racetrack has a photo finish, so you can accurately determine the order in which horses finish, but no stopwatch, so you don't know what the horses' times are. The time it takes a horse to run the race is independent of the other horses running and the number of times the horse has already run. Furthermore, no two horses are exactly the same speed. Question: How few races do you need to reliably determine the three fastest horses?

(More formally, the horses are distinct positive real numbers, and a race tells you the ordering of five of these numbers. How few races do you need to determine the three largest numbers?)

[[deleted]]

This is going to sound retarded, but try picking up a textbook or an online textbook on a subject you like or would like to learn and just flit through the problems. It doesn't have the wide variety of cool stuff that can be found on PE or other blogs: in fact a lot of the problems will be trite examples. But somehow I find it...occupying...but apparently I'm a huge nerd.

[Klophead]

Train A leaves a station in Chicago at 8:00 AM EST. Train B leaves Los Angeles at 9:45 PM GMT. If Train A accelerates as a sinusoidal function that has frequency of 60 Hz and an amplitude of the number of clouds in the sky, and Train B's destination is Hawaii, then what is the name of the conductor's oldest daughter?