i still don't get it im comfused on how many centimeters are there in a decimeter, a meter, and a hectometer

10cm=1dm
100cm=1m
10000cm=1hm

There are 100 centimeters in a meter. We know that becase of the prefix centi-.
Please re-read DrBob222's post. It explains the prefixes clearly. Be sure to use a table until you have the basic prefixes memorized.

If you are confused still then you didn't use my method. You only need to count to six to make any of the conversions you posted.

AND you didn't check into www.google.com and type in the conversion.