Computation Tricks

So, what's the trick? You won't like this - to be good and fast and reliable and sneaky in arithmetic - you have to know arithmetic like the back of your hand! If you know those math facts - addition and the times table, these tricks will be easy to learn. In fact, here are the things you ought to be familiar with:
All these tricks are based on fundamental algebraic principles, plus a lot of good, common sense. Your attitude will make all the difference: there is ALWAYS more than one way to organize your work. Depending on the nature of the problem, some ways can save a GREAT deal of effort, even if they were never taught in grade school! It may be a lot of work to find a shortcut, but once you find it, the problem will always be easier.

And if you want to know the mark of a math professional - she ALWAYS checks her work! Just thinking about how to check your math may improve your skill enormously! One hint about this - NEVER check by doing the same process again. Find some different way to check it. Even if it is a column of numbers you are adding - try adding UP instead of down!

And last of all - if you want to get to Carnegie Hall - PRACTICE, PRACTICE, PRACTICE.
Miscellaneous tricks as I think of them:
The decimal equivalents of 7ths are really easy to learn: 		         ______
1/7 = .142857   (these 6 digits repeat forever)
2/7 = .285714
3/7 = .428571   (have you noticed yet that these are
4/7 = .571428    the same 6 digits in the same order
5/7 = .714285    but starting from a different digit?)
6/7 = .857142   (never a 0,3,6, or 9)
 x/9 = .xxxxxx... (repeating forever) (e.g. 4/9 = .44444444....)
 x/11 = .(9x) repeated forever: e.g. 6/11 = .545454545.....
 x/99 = .0x0x0x0x0x..... e.g. 8/99 = .0808080808...  23/99 = .2323232323.....
Addition tricks Subtraction tricks
 Multiplication tricks
 Division tricks

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