by 100w you mean 20-26 depending on brand

the 100 is just the incandecent equivelant.

using 6 you can grow probly 3-6 plants, depending partially if there from possibly male seeds in which case the cropll be thinned later on.

id suggest get another 2-4 bulbs for 10$ and youll be able to grow about 5-6 females decently after thinning out one or two males in veg