What is the meaning of exponential notation?

Answer 1

The exponential notation consists in writing a number as a value comprised between 0 and 10 and a power of ten. For example

1900 -> 1.9 . 103

0.00023 -> 2.3 . 10-4

It is very useful both to represent very big or small numbers (for example the Avogadro number is about 6.2 . 1023, a n umber that would have 23 digits in normal notation) and to understand the order of magnitude of a number, without taking into account its exact value.

Several times in science an approximate evaluation is needed to understand what is the dimension of something, without evaluating its exact value. In this case calculations can be directly done with exponents rendering them direct and simple.