**Question:** What is scientific notation? Why do we use it in scientific work? Discuss how prefixes are used in measurements and what are the general conventions regarding prefixes.

**Answer**

## Scientific Notation

Writing numbers in power of
ten (or in standard form M * 10^{n}) is called scientific notation.

The internationally accepted practice is that there must be only one digit (non-zero) to the left of the decimal point. So the number 123.4 is written as 1.234 * 10^{2} in scientific notation.

## Why we use it in scientific work

In scientific work we usually deal with very large or very small numbers. Such numbers are always very difficult for writing as well as reading. Mistakes are likely to be done in writing or reading such numbers. For example, number like 1.6 * 10^{-19} will be confusing if wrote in the ordinary method. (0.00000000000000000016). Mathematical operations of such numbers become even more difficult. So to avoid such mistakes, scientific notation has an obvious importance for use.

## Prefixes

There are some powers of ten which are used very frequently in scientific work. They are given special names and symbols and called ‘prefixes’. Some of them are given in the following table.

## General conventions about prefixes in measurement

Following are the accepted rules (conventions) about the use of units and prefixes.

(1) Full name of the unit does not begin with a capital letter even if named after a scientist. For example, newton is the name of the unit and Newton is the name of the scientist.

(2) If a unit is named after a scientist and it has a single letter, it is written in capital, like N for newton. If the unit has two letters, the first one is capital and second one is small, like Pa for Pascal.

(3) The prefix is written before the unit and adjacent to it, like 5 pF.

(4) The combination of units is written each with one space apart, for example torque = 50 N m.

(5) When a multiple of base unit is raised to a
power, the power applies to the whole multiple, for example, 1 km^{2} =
1 (km)^{2} = 1(10^{3}m)^{2} = 1*10^{6} m^{2}.

(6) Double, triple prefixes are not allowed. 1 μμF, for example, is not legal. Instead, write 1 pF.