Scientists use scientific notation to represent very small or very large numbers because this notation increases the
accuracy of measured quantities.
convenience in using the numbers.
number of significant figures.
precision of measurements.

convenience in using the numbers.

Explanation:

Very small numbers have too many digits, similar to large numbers.

This numbers can take too much space and therefore cause inconvenience during recording or calculation.

To avoid this inconvenience, scientists use scientific notations in representation of this numbers.

Some examples of the notations are:

answer: 21

step-by-step explanation:

divide 630 by 30. 30 goes into 630 21 times