100 Light bulbs

There are 100 Light bulbs in a sequence, all kept in OFF state. The first person comes and toggles all the bulbs which are at position that is multiple of $1$, i.e. switch all bulbs to ON. The second person toggles all multiples of $2$, i.e. turn the even numbered bulbs OFF and leave the odd ones as is. The third person comes and toggles all multiples of $3$. This process continues till the $100^{\text{th}}$ person do their part. After this, how many bulbs are in ON state?