Three times the fifth power of e. Or Three times e's fifth power.
> 3 x 10^5 (=300,000).
Three to the exponent of five.
A calculator user once suggested "decapower." I think exponent and "EXP" are comfortable and easy to say and are ingrained to most old school calculator users. Which is also why I think "e's fifth power" can be a more natural sequence.
I think that's still ambiguous. The base of the exponent is implied, and there are decent arguments or fields in which the assumed base of 10 isn't universal. In your "Three times e's fifth power." version, you needed so specify e. I think for accuracy it's also needed to specify 10 in that "Three to the exponent of five." case.
(Having said that, there are certainly cases where the 10 as the base of the exponent will be clear/unambiguous from the context. )
Three to the power of five.
> 3 x e^5
Three times the fifth power of e. Or Three times e's fifth power.
> 3 x 10^5 (=300,000).
Three to the exponent of five.
A calculator user once suggested "decapower." I think exponent and "EXP" are comfortable and easy to say and are ingrained to most old school calculator users. Which is also why I think "e's fifth power" can be a more natural sequence.