There are infinitely many primes, and we could never discern infinitely many
notes, so we will make the number of notes finite using a standard number theory
tool--modular arithmetic.

Method Two: Rather than use the primes themselves, we divide each prime
by a fixed number and then just play the remainders. The fixed number is then
called the modulus or base. For example, if we choose seven as our modulus, then
for the primes {2, 3, 5, 7, 11, 13, 17, 19, 23, ...} we would play {2, 3, 5, 0, 4,
6, 3, 5, 2, ...}. These would be rather low notes (using the midi standard), so
to place them near the center of the keyboard I add a constant (such as
55).

Why not listen to the primes (modulo seven) as you
answer the following questions? (You may also click on the eye to
see the "musical" score.)

You might be able to separate these notes better by ear if we use a
different percussion sound for each note (each remainder modulo seven).