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This question has always stumped me since using a simple basic calculator over 20 years ago. I'm using the basic calculator on windows or it can be any for that matter.

I input the following into the calculator: 1 / 15000

The output is this: 6.666666666666667e-5

  • What is this number format called?
  • Why is there an e-5 at the end?
  • Why 6.66666?
  • And last of all, how do I convert this back to regular decimal places from that output: .00006
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  • $\begingroup$ A closely related notation is usually called Scientific Notation. In scientific notation one would write the number as $6.66666666667\times 10^{-5}$. Your variant is sometimes called E-notation. It is used on calculators because $e$-$5$ is more compact than $\times 10^{-5}$. $\endgroup$
    – André Nicolas
    Oct 13, 2014 at 23:49

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1.) The number format is called scientific notation. Follow the link left for you in the comments to find out more.

2.) The e-5 at the end indicates that the actual number has the decimal shifted 5 places to left of what is in the display, so 6.6666666667e-5 = 0.000066666666667.

3.) The decimal is shifted so that you can see more significant digits without making the display larger.

4.) My second answer tells you how to do that.

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  • $\begingroup$ what if i wanted to do the shifting with the simple calculator? $\endgroup$
    – Patoshi パトシ
    Oct 13, 2014 at 23:51
  • $\begingroup$ Actually the only reason you would want to convert the number is for display purposes, which is easily done by hand. You can also calculate in scientific notation by hand. I am sure there is information about it in the link Andre provided. $\endgroup$
    – Laars Helenius
    Oct 13, 2014 at 23:54
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Scientific to decimal

Converting a number from scientific notation to decimal notation, first remove the x 10n on the end, then shift the decimal separator n digits to the right (positive n) or left (negative n). The number 1.2304×106 would have its decimal separator shifted 6 digits to the right and become 1 230 400, while −4.0321×10−3 would have its decimal separator moved 3 digits to the left and be -0.0040321.

1/ 15000 = 6.666666666666667e-5

6.666666666666667e-5 = .000067

now the question is how do you convert it back to decimal using the simple calculator. sure i can do it with pen and paper.

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