Topic: Tricks, Rules & Methods

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Wednesday, February 27, 2008 - 01:28 PM

Posted by Farisnet

22616 Reads

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.

Sunday, June 24, 2007 - 03:23 PM

Posted by neogeniis

12595 Reads

You may have learned early in Algebra that the difference of squares is (A+B)(A-B) Later on you may have even learned a shortcut to factoring sums and differences of cubes. I have constructed a series of algorithms to factor expressions in this form (A^p±B^p)

Tuesday, May 22, 2007 - 09:13 AM

Posted by dvdhn

11832 Reads

If a car travels east at a speed of 30 miles per hour from Point A to Point B and from Point B, the car travels back to Point A at 60 miles per hour, what is the average speed of the car?

Friday, June 02, 2006 - 06:20 AM

Posted by ScottC

87066 Reads

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.

Saturday, May 20, 2006 - 05:38 AM

Posted by hendry78

15957 Reads

This is a technique which I devised a long time ago (not sure if anybody else thought of this method). It proved to be very useful to me and I think it will be useful for everyone, too.

Saturday, May 20, 2006 - 05:35 AM

Posted by uzaircse

11863 Reads

Here's a trick to calculate 5th root of any two digit number of a perfect 5 power.

Saturday, May 20, 2006 - 05:28 AM

Posted by SRAD

12593 Reads

This is a quick trick you can pull off when playing dominoes with your friends by guessing the hidden domino, it's really simple!

Saturday, May 20, 2006 - 05:26 AM

Posted by MikeMomo

8344 Reads

If you would like to square a number easily you can basically take the numbers distance from 25 and multiply that by 100. Then you take the numbers distance from 50 and square it. Finally you add the two numbers together.

Sunday, May 14, 2006 - 04:01 PM

Posted by Silke

13945 Reads

I was doing a lesson with my grade 6 students on equivalent fractions. We were looking at patterns for 1/2. We covered all the conventional patterns the students could find (as well as the ones I had thought of), when one of my students put up his hand and said he found another pattern.

Sunday, May 14, 2006 - 03:36 PM

Posted by pure_aatma

7818 Reads

Here is an interesting way to find out the square of different numbers.

Sunday, May 14, 2006 - 03:29 PM

Posted by Ruffnekk

8726 Reads

Yet another fine - and very easy-to-learn - trick for multiplying by 11.

Sunday, May 14, 2006 - 03:03 PM

Posted by shhhcant

6067 Reads

A trick to quickly find x=9a in your head, where a is the multiplier.

Saturday, March 11, 2006 - 06:07 PM

Posted by Mohsin

12122 Reads

Another twist on how to multiply two 3-digit numbers mentally

Saturday, March 11, 2006 - 05:16 PM

Posted by ArunChaganty

27174 Reads

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.

Sunday, November 27, 2005 - 09:51 AM

Posted by RyanJ

9811 Reads

Here is an interesting one to impress your friends that involves squares and quadratics.

Sunday, September 11, 2005 - 03:19 PM

Posted by sahil

8896 Reads

This squaring trick uses the algebric property of multiplication (a+b)(a+b)=a²+2ab+b².

Tuesday, July 19, 2005 - 10:54 PM

Posted by CppA

9858 Reads

Here I will show you how to compute the number of edges in a complete graph with n vertices.

Monday, July 18, 2005 - 11:44 AM

Posted by j2020j0908

112798 Reads

The trick I am going to explain is called the cross-multiplication technique... but not the one you know.

Tuesday, March 15, 2005 - 11:58 AM

Posted by erlkonig

13203 Reads

This trick is quite simple. All you have to know is to square a number (multiple articles on that here at CuriousMath.com) and basic subtraction.

Sunday, February 27, 2005 - 03:30 PM

Posted by Didd

13772 Reads

Here's an interesting method for squaring any two digit number.

Monday, December 27, 2004 - 06:30 AM

Posted by mathmate

56699 Reads

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.

Saturday, December 11, 2004 - 03:04 PM

Posted by mathmate

50041 Reads

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.

Wednesday, December 08, 2004 - 07:21 AM

Posted by guil140

87095 Reads

With the help of logarithms, you can do some pretty amazing mental calculations. This article shows you how.

Friday, October 29, 2004 - 06:46 PM

Posted by spudgeuck

15564 Reads

I think this formula will appeal to everyone (well I hope it will!) It was inspired by the story of Freidrich Gauss and his teacher.

Wednesday, October 20, 2004 - 08:46 AM

Posted by allennash

32723 Reads

This method is a very simple way to find the sum of numbers.

Tuesday, August 24, 2004 - 07:39 AM

Posted by Priyanjana

10402 Reads

If you want to find a nth power of a two- digit number, you can modify the Binomial Theorem as follows.

Monday, August 09, 2004 - 10:20 PM

Posted by paramesh

10818 Reads

A method for squaring two digit numbers.

Monday, August 09, 2004 - 10:01 PM

Posted by sancle

9752 Reads

A series of observations and tricks regarding the square.

Monday, August 09, 2004 - 09:49 PM

Posted by Fruldy

10195 Reads

This problem is inspired from Fun With Mathematic by Jerome S. Meyer 1961.The part of the book that talks about the repeating pattern of last digit has never formulated as a problem to let other people understand the concept of last digit of a number raise to the power. For 43 years, this concept has never been introduced to the student.

Monday, August 09, 2004 - 09:33 PM

Posted by flyers2000

54622 Reads

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).