Naming cyclodienes

[Angela_Pu_3C]

On pg 29 of intro to orgo, the ex under "unconjugated dienes" reads as "Cyclohex-1,4-diene." However, for self-test 1.11A part B (on the bottom of the same page), the answer reads as "1,6-Dimethylcyclohexa-1,4-diene." Pg 30 continues with ex like "cycloocta-1,5-diene" and "cyclododeca-1,3,5-triene." My question is, is hex or hexa (or oct vs octa, dec vs deca, etc) correct? Or are they interchangeable? Thank you

[Stephanie_Younan_3D]

You have to add to add a vowel (a) at the end of hex (hexa) or pent (penta) so that two consonants are not next to each other in the name.