Why is the metric system used instead of the us customary system, and vice versa, in various parts of the world?

Easy to manipulate. Conversions are based on multiples of 10

Step-by-step explanation:

The metric system is a universal system used throughout the world. The reason its is so widely used is because it is easily to manipulate and most of the conversation are based on multiples of 10, you just have to move the decimal places.

The English system on the other hand my seem complex but it is easy to understand because units are usually based on human body parts, for e.g. the yard is loosely based on the length of your arm

we don't have enough info to solve this