Can someone tell me what these parenthesis mean?

[flyingpig]

Homework Statement

Draw this organic molecule (CH₃)₃CCH₂CH(CH₃)CH₂CH₂CH₃

The Attempt at a Solution

My smart friend tells me it is 2,2,4-trimethylheptane.

But I counted and I got octane, what does the parenthesis mean??

 

[NobodySpecial]

(CH₃)₃CCH₂CH(CH₃)CH₂CH₂CH₃

The first paranthesis means the group in parenthesis is repeated the number of times in the subscript, the second set mean that the group is separate and attached to the atom next to it.