How can I convert 7.8 x 10^-3 to 39/5000 using a calculator?

[Loonyplz]

how would i convert 7.8 x 10^-3 = 39/5000 / 7.8 x 10^-3 into a fraction on my calculator?

I know the result is 0.0078 but I don't know how to get it, thanks!

 

[willem2]

You want to start with 7.8 x 10^-3 and end up with 39/5000 ?

10^(-3) = 1/1000, so 7.8 x 10^-3 = 7.8/1000. Multiply the numerator and the denominator by 10 to get integers and you end up with 78/10000. Remove common factors from this and you get the answer.