Huckels rule
 

In Huckels rule how do you determine what number is substituted for n? For example, in benzene n=1. Where does the 1 come from?

Hi
Huckels rule means 4n+2= number of electrons in the compound.
benzen has 6 electrons that mean 4n+2=6 that mean n = 1

n can be any positive integer. Benzene has 6 electrons in it's aromatic conjugated system; 4n+2 = 6 gives an n = 1. An aromatic compound with n = 2 will have 10 electrons in it's aromatic system.