Help Strange problem with scientific calculator.

[sunny79]

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.

 

[adjacent]

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

The correct answer for this is 5.7 x 10^-106

Welcome to PF
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)

 

[Borek]

It is called an "arithmetic underflow".

Note that

$$\left(\frac 1 {4.2 \times 10^{52}}\right)^2 = \left(\frac 1 {4.2}\right)^2 \left(\frac 1 {10^{52}}\right)^2 = 0.057 \times \frac 1 {10^{104}} = 0.057 \times 10^{-104}$$

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.

 

[sunny79]

Thanks guys, that helped a lot. :)