Answer:
987.76 Hz
Explanation:
You have B4's frequency of 493.88 Hz and you want to know the frequency of the note one octave above B4.
When you go up an octave, you double the original frequency. When you go down an octave, you divide the original frequency by two.
So, since B4's frequency is about 493.88 Hz, an octave above would be 2 x 493.88 Hz or 987.76 Hz
If we were looking for an octave below B4, we would divide 493.88 Hz by 2 to get 246.94 Hz.