By now you should be able to figure out how numbering is done.

2-Chlorobuta-1,3-diene

(CH₃)₂C=CHCH₂CHO

We may also write it like this :

4-Methylpent-3-en-1-al

OHC-CHO

Ethane-1,2-dial

Look, how N is used to write the alkyl group of other side of amide

3-Ethyl-N-methylhexan-1-amide

[(CH₃)₂CH]₃COH

2,4-Dimethyl-3-(1-methylethyl)pentan-3-ol

How?

Because it can be simplified as :

CH₃CHOHCH₂CH(CH₃)CH₃

4-Methylpentan-2-ol