[msrky17]

what is quantum number?

[mitch.fsu]

google "quantum number"

... theres a wiki page on it

[S.V.]

The principle quantum number (denoted n) is the same as the shell number. It can range from 1 to 7. n=0, n=1, n=2, and n=3 correspond to the s-, p-, d-, and f- orbitals, respectively.
The Azimuthal quantum number (denoted l) is the angular momentum. It can range from 0 to n-1. For example, if you have n=4, l can be anywhere from 0 to 3.
The magnetic quantum number is denoted m_l and can range from -l to l. For example, if you have l=3, then m_l can range from -3 to 3.
The spin magnetic quantum number is denoted m_s and is always +1/2 or -1/2 and relates to electron spin.