[megh44]

i dont understand brackets...
for example
ch3 (ch2)3 C O N ch3
                      |
                   CH2CH3
i thought the answer would be:
N-ethy-N-methylpentanamide
but the answer is:
N-ethy-N-methyl-2,2-dimethylpropanamide

Please help me understand what brackets do!

[Mr Peanut]

The parenthesis simply delimit the functional group that is being repeated. The subcripts would be confusing without them.

CH3 CH2(CH3)2 C O N CH3
                      |
                   CH2CH3
is N-ethy-N-methyl-2,2-dimethylpropanamide

and


CH3 (CH2)3 C O N CH3
                      |
                   CH2CH3
is (as you suspected) N-ethy-N-methyl-pentanamide