[mitko1994]

hello, i have a question i just can't figure out .

Why is 2-methyl 1,4 cyclopentadiene wrong???

the textbook says the right answer is 1-methyl 1,3 cyclopentadiene
  but i want to know why. So please explain the mistake

Thanks

[Matias Ekstrand]

2-methyl cyclopenta-1,4-diene does not yield the lowest number on the substituents or the main functional group. There is another spot you may begin counting from that gives you 1-methyl cyclopenta-1,3-diene