A note one octave above 1000 Hz is 2000 Hz. A note two octaves above 1000 Hz is 4000 Hz. A note one octave below 1000 Hz is 500 Hz. A note two octaves below 1000 Hz is 250 Hz.
Work Step by Step
If you multiply the frequency of a note by 2, you have the same note, but in the next higher octave. If you divide the frequency by 2, you drop down one octave.