Wed, 11 Nov 2009 07:26:12 -0800 http://www.curiousmath.com/ CuriousMath.com en-us http://www.curiousmath.com/images/cm09.jpg http://www.curiousmath.com/ clay@curiousmath.com http://www.curiousmath.com/index.php?name=News&file=article&sid=95 Here's a quick way to sum a sequential series of numbers. Wed, 11 Nov 2009 07:26:12 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=94 By summing the correct continuous series of cubed numbers it is possible to produce a number which is itself a cube. Mon, 26 Oct 2009 08:52:52 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=92 There exist numbers which have not just one but two positive cube roots, such as for instance, the number 1729, which is the result of 93 + 103 and 123 + 13. This article proposes an algorithm that produces an infinite supply of such numbers as well as presenting "near misses". Mon, 31 Aug 2009 11:06:37 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=91 Since the third century B.C. when Eratosthenes determined the first tables of the prime numbers, the number 1 has never been considered to be prime because its roots were easily determined as (-1)x(-1)=(+1). Because no doubts appeared about this definition the usual sequence of prime numbers has been accepted as 2,3,5,7,11,13... Thu, 30 Jul 2009 09:06:28 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=90 In honor of Pi Day 2008, I thought I would post a little article about the remarkable, infinite, and irrational Pi. Fri, 14 Mar 2008 07:51:51 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=89 As inspired by Gauss's tale of impressive summation of all integers from 1 to 100, I set out to have a formula that would sum all the numbers between two numbers, inclusive. Wed, 27 Feb 2008 10:28:25 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=79 Clay's article was an excellent, and a very well explained one too. I'd just like to add the bit about the probability of the odds of finding a person with the same birthday as you. Hopefully mine will be as descriptive as his. In this article, we shall explore some techniques of probability, and 'permutations and combinations'. This is going to be a slightly long article, but is very much educative, and I'll try to cover the entire thing from front to back. You can skip bits if you know them, but for the benefit of those who don't I've included them. I've finally posted a way of doing the question without any of this knowledge, but I still think you should read and understand what I'm trying to explain. Thu, 16 Nov 2006 17:26:55 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=78 Here's a fun and easy application of probability to show the odds are good that at least two people in a relatively small group will share the same birthday. Thu, 17 Aug 2006 20:19:01 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=77 When asked to do division in your head, it's very impressive to be able to carry the answer out to several decimal places. When dividing by a 1-digit number, it's not that difficult, either. Fri, 02 Jun 2006 03:20:36 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=64 This is one of the best methods used to create a magic square of any order. I will start with an example of 3*3 grid to explain the method. Sun, 26 Mar 2006 03:46:32 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=61 Two days before my major exam, my friend and I sat down to play with magic squares. Obviously a big mistake, but I actually did the best of all in that particular exam. I think it came from cracking the code for any odd magic square. Sat, 11 Mar 2006 14:59:31 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=60 This is a rather well known concept (at least where I'm at), but I thought I might as well post it. I proved it yesterday, and so I thought I'd share it with you all. Sat, 11 Mar 2006 14:16:56 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=56 The sum of any cube when reduced to a single digit will always be either 1, 8, or 9. Sun, 27 Nov 2005 06:57:45 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=52 The trick I am going to explain is called the cross-multiplication technique... but not the one you know. Mon, 18 Jul 2005 08:44:12 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=51 The other day I was strolling in a part of the city where street vendors compete for the tourist dollar. I came across a young lady, felt marker in hand in front of an easel displaying a 6x6 array of numbers. It was a hot day, and it took an effort just to stand among the crowd at the same time understand what she was explaining. Curiosity won over me and here's what I found. Sun, 26 Jun 2005 05:13:14 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=45 You probably know that 32 + 42 = 52. Those three whole numbers, known as "Pythagoras Triplets", satisfy the Pythagoras Theorem, a2 + b2 = c2. Did you know there are many more such whole number triplets? This article shows you one method of finding them. Mon, 27 Dec 2004 03:30:44 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=44 You may have heard the recent news of Dr. Gert Mittring, who correctly extracted the 13th root of a 100-digit number in less than 12 seconds...in his head. This article shows you how to accomplish the same feat in the same amount of time using an ordinary calculator. Sat, 11 Dec 2004 12:04:24 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=43 With the help of logarithms, you can do some pretty amazing mental calculations. This article shows you how. Wed, 08 Dec 2004 04:21:44 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=39 No symbols and characters allowed. (Here's a hint: it's not 999) Tue, 07 Sep 2004 08:25:23 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=32 I came up with this method for determing the logarithm (base 10) of a number in my head back in 1995. I was tutoring a friend for her MCAT exams and a question involving pH and pKa values struck my interest. Although we were able to arrive at a suitable answer without actually needing a calculation, I still wanted a quick way of determining logarithms in the event that I found myself without a calculator (and just as a mental challenge for myself). Mon, 09 Aug 2004 18:33:35 -0700 http://www.curiousmath.com/index.php?name=News&file=article&sid=28 Here's how you can directly write down the answer to any number multiplied by 11. Thu, 26 Feb 2004 13:01:12 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=27 Got 5 minutes to spare? That's all the time you need to learn how to quickly multiply two numbers from 11 to 19 in your head. Thu, 26 Feb 2004 12:57:44 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=25 Ask anyone to select a number less than 1000, and to divide it respectively by 7, 11, and 13, giving you the three remainders. You will then be able to tell him what number he originally selected. Mon, 15 Dec 2003 08:02:41 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=24 Like they said, it’s hip to be square! Here are a few easy tricks that’ll make squaring numbers much faster. Tue, 28 Oct 2003 12:15:13 -0800 http://www.curiousmath.com/index.php?name=News&file=article&sid=23 If you want to add all the numbers from F (First) to L (Last), here is an easy way to do it, and many times can be performed in your head. Tue, 30 Sep 2003 08:58:14 -0700