Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    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


    User Avatar

    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. :)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook