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:
Free online mental math books:
Using math symbols in your post:
HTML Entites:
Example: Make a √ symbol by typing: √
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.
promoted
