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Currently I am preparing for trading exams which tests faster arithmetic skills. For ex- 80 questions (like calculating 0.abc* 0.cd) to be done in 8 minutes.

I am trying to memorize the squares and tables and using simple tricks to solve these but still I am able to reach up-to 40 questions.

Any suggestions on how to increase my speed for such calculations. Any books or links are appreciated.

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  • $\begingroup$ What examples do you struggle on? you say you can do 40 in 8 minutes, so what slows you down? $\endgroup$ – Joshua Lochner Jul 27 '16 at 19:14
  • $\begingroup$ Those which involve fractions. Its mainly the problems involving decimal that I struggle with. $\endgroup$ – uzumaki Jul 27 '16 at 19:20
  • $\begingroup$ The decimal is no problem. Just multiplicate and shift the comma to the left. Just count the decimals after the commata to see how far you have to shift. $\endgroup$ – Peter Jul 27 '16 at 19:20
  • $\begingroup$ @Peter not all questions were of multiplications. It included addition and subtraction too $\endgroup$ – uzumaki Jul 27 '16 at 19:21
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    $\begingroup$ Are these more or less random digits you're calculating? Any patterns like multiplying by $0.25$, $0.125$, etc.? $\endgroup$ – John Jul 27 '16 at 19:30
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Depending on how much time you have to prepare, it is hard to beat Arthur Benjamin's Secrets of Mental Math. The Contents in case you are interested and to see whether or not you think it may meet your needs:

  1. Mental Addition and Subtraction
  2. Basic Multiplication
  3. Intermediate Multiplication
  4. Mental Division
  5. The Art of "Guesstimation"
  6. Pencil-and-Paper Math
  7. Memorizing Numbers
  8. Advanced Multiplication
  9. The Art of Mathematical Magic

Manipulation of decimals and the like occurs in chapter 4 on mental division. Personally, I have only worked through the first few chapters, but I was surprised at how effective everything he puts forth is.

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  • $\begingroup$ Thanks, I would give it a try then $\endgroup$ – uzumaki Jul 27 '16 at 19:36
  • $\begingroup$ Keep in mind that it is a book even though a small and simple one. Mastering the techniques Art puts forth will take a fair amount of time. $\endgroup$ – Daniel W. Farlow Jul 27 '16 at 19:37

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