Question

why there is number of systems for writing units?​

Answer 1

Answer:

The SI system, also called the metric system, is used around the world. There are seven basic units in the SI system: the meter (m), the kilogram (kg), the second (s), the kelvin (K), the ampere (A), the mole (mol), and the candela (cd).

Answer 2

Explanation:

There are as many units as there are independent quantities. We consider length, mass and time three quantities which are independent of each other. Hence they have three separate units for their measurements. Hence it is required to define systems of units