What is a decemeter?

In general deci means 1/10th part of the measure mentioned along with it .In this case the measure mentioned is meter.So decimeter means 1/10th ofa meter which means 100centimeters.

As far as I know the above, unless I'm having a very bad day is incorrect. There are 10cm in 1dm. There are 100cm in 1M therefore there are 10cm in one dm (100/10).