Divisibility Rule of 7, 13, 17, 19, 23, 29, 31, 37, 41, 43 and 47
You might have seen divisibility rules of various numbers. But most of them very conveniently skip the ones which are very difficult and a divisibility rule for which is very much required. This post includes the divisibility rule for some such numbers like 7, 13, 17, 19, 23, 29, 31, 37, 41, 43 and 47.
While reading this you have to be little patient. Read this carefully and try to apply it practically. If you master divisibility rules or tests explained below, I am sure these will come very handy in various examinations including competitive ones.
Quick Multiplication up to 20 x 20
“I’m having trouble above 10x10.”
This was a statement I heard many times while interacting with students preparing for competitive examinations including CAT. This was in response to my appeal to them to memorize tables up to 20x20.
Today I am posting here on QuickerMaths.com, the method which I recommend to my students too.
How to multiply up to 20x20 in your head?
Assumption: You know your multiplication table reasonably well up to 10×10.
I am trying to explain this with an example,
Perfect Square Puzzles
Squaring Puzzles- Find below 2 interesting puzzles related to square of some number. Hope you will like them.
Puzzle 1
The square of 13 is 169. Take the last digit of the square, 9, and place it in the middle, making 196. This is the square of 14, the next number above 13.
What are the next numbers which also have this property?
Puzzle 2
The following multiplication example uses every digit from 0 to 9 at least once. Letters have been substituted for the digits. Can you replace the letters and make the original multiplication problem?
B O G
x B O G
_______________
L Y L E
G G U L
T U O O
___________________
U N I T O E
Beauty of Numbers
In this post I am sharing with some very interesting numerical symmetries. I got it from varied sources but the most interesting is the book from Shakuntala Devi titled Figuring: The Joy Of Numbers. It's a must read for all math lovers.
So here you go -
1 x 8 + 1 = 9
12 x 8 + 2 = 98
123 x 8 + 3 = 987
1234 x 8 + 4 = 9876
12345 x 8 + 5 = 98765
123456 x 8 + 6 = 987654
1234567 x 8 + 7 = 9876543
12345678 x 8 + 8 = 98765432
123456789 x 8 + 9 = 987654321
Mind Boggling Math Puzzles: Millennium Prize Problems
Quicker Maths offers regular tips and tricks for zooming through some arithmetic problems, as well as giving us fascinating puzzles that offer some solid food for mathematical thought. But what if you were given the opportunity to earn one million dollars to solve one math problem? That's exactly the deal that the Clay Mathematics Institute in Cambridge Massachusetts has offered. And pretty much anyone can enter to win.
The Millennium Problems, as they are known, were originally seven math problems that had existed for several years and remained unsolved. Most recently, one problem--the Poincare Conjecture--was successfully solved by Dr. Grigory Perelman of St. Petersburg, Russia. Perelman worked on and solved the problem in 2002 and 2003, and was thereafter awarded the CMI one million dollar prize in 2010, although he ended up turning down the prize money.
Who is behind QuickerMaths?
I am Vineet Patawari - PGDM (IIM Indore), ACA, B.Com(H). My passion for Mathematics, specially Vedic Maths encouraged me to start QuickerMaths
I believe that if trained properly using powerful tools like Vedic Maths, the immense intellect of human mind can be ignited instantly - find out more
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Recent Comments
watchman was paid for awaking not for sleeping so that he can see dreams.. – 05Feb12
as a night watchman he shouldnt have slept at night to get that dream... – 04Feb12
Can u plz give me clarity in ur solution Kaush sir..... – 04Feb12
thanks for these tricks. Are these from the book "quicker maths by m.tyra" ? – 03Feb12
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