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Hot New Top Rising Controversial

r/mentalmath • u/WillowSingle8174 • 14h ago

Just published my first book – 11 years in prison, and this is my shot at freedom.

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MentalMath: It's the thought that counts

r/mentalmath

Want to learn how to do math in your head, or even just wrap your head around a mathematical concept? This is the place!

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Mental Math: It's the thought that counts!

Thanks to /u/claymazing for the inspirational subtitle!

Official /r/MentalMath wiki
(Self-contained downloadable ZIP file)

New additions (June 30, 2017):

  • Division by 10n+9
  • Rule of 72 (2× principal)
  • Rule of 96 (2.5× principal)
  • Rule of 114 (3× principal)
  • Rule of 132 (3.5× principal)
  • Rule of 144 (4× principal)
  • Rule of 156 (4.5× principal)
  • Rule of 168 (5× principal)
  • Combining rules (Up to 25× principal)

Mental Math Sites:

  • BEATCALC
  • BetterExplained.com
  • /r/CasualMath
  • CuriousMath (Archived)
  • Flying Colours Maths
  • /r/funmath
  • Grey Matters
  • Intuitive Calculus
  • Math Dude
  • Math-Magic.com (Archived)
  • Math Memoirs
  • Math StackExchange
  • Math Tricks For Kids
  • Math Vault
  • Mental Math Guide
  • MindMagician.org
  • Numberphile
  • Plus Maths
  • Quickermaths
  • The Math Behind The Magic

Free online mental math books:

  • 101 Shortcuts in Math Anyone Can Do by Gordon Rockmaker
  • Cracking the Mental Math Code: A Repertoire of Number Sense Techniques by Yash Chandak
  • General Method for Extracting Roots using (Folded) Continued Fractions by Manny Sardina
  • High Speed Math by Lester Meyers
  • How to Become a Lightning Calculator by John Regan
  • Inner Algebra: How To Do Algebra In Your Head by Aaron Maxwell
  • Integrate Your Brain: How To Do Calculus In Your Head by Aaron Maxwell
  • Math and Memory Short Cuts
  • Mathematician's Delight by W.W. Sawyer
  • Manu-Mental Computation by Woodford Dulaney Anderson
  • Nix The Trix by Tina Cardone
  • Number Sense Shortcuts for Beginners by Larry White
  • Number Sense Tricks by Bryant Heath (Dropbox Mirror)
  • The Power of Vedic Maths by Atul Gupta
  • Practical Short Methods in Rapid Calculation by William Bell
  • Quick And Easy Math by Isaac Asimov
  • Rapid Calculations by A. H. Russell
  • Secrets of the Calculation Artist by Philipp Maennchen
  • Short-Cut Math by Gerard W. Kelly
  • The Speed Math Bible by Yamada Takumi

Using math symbols in your post:

HTML Entites:

Example: Make a √ symbol by typing: √

  • Mathematical symbols
  • Fractions
  • Greek letters
  • Subscripted and superscripted characters

Courtesy of jamt9000, you can also display subscripted and superscripted characters:

  • *_subscript_* makes subscript

  • *`superscript`* makes superscript

  • *_sub_`sup`* makes subsup

  • *`sup`_sub_* makes supsub

  • *`169`*⁄*_231_* makes 169⁄231

NOTE: The ` character is called the grave accent. On desktops and laptops, you’ll find it on the tilde (~) key. On most mobile devices, it can usually be accessed by holding down either the apostrophe or tilde keys.

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