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Help Strange problem with scientific calculator.

  1. Mar 2, 2014 #1
    Help!!!Strange problem with scientific calculator.

    I was doing chemical equilibrium problems where one of the steps required me to square the reciprocal.

    Which was (1/4.2x10^52)^2

    The correct answer for this is 5.7 x 10^-106 but my Casio FX 115 ES calculator keeps showing zero.

    Can anyone please shed some insight on this. It would be greatly appreciated. I have used this calculator in the past with success. I never encountered such a problem before. I have my exam on Tuesday. BTW no graphing calculators are allowed. If this doesnot workout then I will have to purchase another scientific calculator.
  2. jcsd
  3. Mar 2, 2014 #2


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    Gold Member

    Welcome to PF :smile:
    The calculator can't show a value greater than 99 or less than -99 in the power.(The maximum value available is 9*10^99 and minimum is (9*10^(-99))
    (I have a Casio fx-100MS)
  4. Mar 2, 2014 #3


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    Staff: Mentor

    It is called an "arithmetic underflow".

    Note that

    [tex]\left(\frac 1 {4.2 \times 10^{52}}\right)^2 = \left(\frac 1 {4.2}\right)^2 \left(\frac 1 {10^{52}}\right)^2 = 0.057 \times \frac 1 {10^{104}} = 0.057 \times 10^{-104}[/tex]

    10-104 part can be done in memory faster than it takes to key numbers into calculator - you just need to understand what is going on and how to deal with such a situation.
  5. Mar 2, 2014 #4
    Thanks guys, that helped a lot. :)
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