Given a note, ex. A4 is 440 Hz, moving up an octave, or 12 semitones, is doubling the Hz. You can figure out the Hz from the base note by multiplying it by 2^(x/12) where x is the number of semitones you want add.

I’m not sure you understand the parent comment. I didn’t realize how terrible until I hailed a cab, noticed someone who was actually also hailing but must have been doing so before me, so I deferred and offered the cab I hailed to him. The cabby noticed the person was black and just booked it. The person was resigned and indicated this was not uncommon.