If you think about this  it's based on the four carbon structure  so you've gotta have a few in the name  there is a carbon carbon double bond  so the basic structure we've got is the Butane  but as  there is more than one position you could have that  carbon carbon double bond  now, to indicate this position  and so this one would be called  futes  it would normally be a  butane  but to indicate it's position  bute one E  and again you're taking the lowest number  so instead of it being a bute three, it's a bute one E  you start at the appropriate .