it is a type of metrex unit
Yes, the abbreviation for decameter is often written as "dam." A decameter is a unit of length in the metric system equal to ten meters. It is commonly used in various fields such as science and engineering to measure longer distances.
You need to check your spelling there, it can't be 'desa...', it will be either a decametre or a decimetre. Centi- (c-) = x 0.01 (one hundredth) Deci- (da-) = x 0.1 (one tenth) Deca- (d-) = x 10 (ten) Kilo- (k-) = x 1000 (thousand) So, 1 dam is equal to 10 m, and 1 dm is equal to 0.1 m, which is the same as 10 cm. From that, you can see that: 1 km = 100 dam 1 km = 10,000 dm