Doing Fractional Exponents on Basic Scientific Calculator

[bballwaterboy]

Suppose you have 8^-1/3 and want a precise value for it. How would you go about calculating this on a regular scientific calculator.

I punched in:

8, then the exponent button, then 1, then negative, then division, and finally 3. The calculator reads "error."

 

[mfb]

Use -0.33333... with as many digits as your calculator accepts. The error will be comparable to usual rounding errors, and the calculator would not calculate it more precisely even if you find a way to enter "-1/3".

 

[SteamKing]

Suppose you have 8^-1/3 and want a precise value for it. How would you go about calculating this on a regular scientific calculator.

I punched in:

8, then the exponent button, then 1, then negative, then division, and finally 3. The calculator reads "error."

It's not clear what a 'regular scientific calculator' means. Some calculators use algebraic entry; some use reverse Polish notation (primarily the HP brand).

This is a question which is best left up to the user's manual.

In any calculator, you can always use logs to calculate 8^-1/3.

log (8^-1/3)) = -(1/3) log (8) = -log (8) / 3. The answer is then 10^-log(8)/3

You can also use natural logs and e^x to convert the natural log back into a number.

 

[HallsofIvy]

Or you could just enter "1/2" to begin with!