Scientific Notation

Scientific notation (also known as standard form) is used for numbers that are either very large or very small, like the following.

The distance from the Earth to the nearest star system, Alpha Centauri, is about

39 900 000 000 000 000 m

Red light has a wavelength of about

0.000 000 7 m

Scientific notation is a more convenient way of expressing such large or small numbers. It is used extensively in science and engineering, and makes life easier when working with large (or small) numbers on calculators or computers.

Scientific Notation - Definition

A number in scientific notation is expressed as

P × 10^k where: 1 ≤ P < 10 and k is an integer

Example 1

(a) 340 000 000 (ordinary notation)

= 3.4 × 100 000 000

= 3.4 × 10⁸ (scientific notation)

(b) 0.000 015 (ordinary notation)

= 1.5 ÷ 100 000

= 1.5 × 10^-5 (scientific notation)

(c) 682 500 000 (ordinary notation)

= 6.825 × 8

= 6.825 × 10⁸ (scientific notation)

To change a number from scientific notation to ordinary notation, we simply reverse the procedure shown in the above examples.

Example 2

Using scientific notation, we can write our earlier examples as:

Distance to Alpha Centauri:
39 900 000 000 000 000 m = 3.99 × 10¹⁶ m
Wavelength of red light:
0.000 000 7 m = 7 × 10⁻⁷ m

Example 3

We are all affected by slow Internet connections, but German scientists in 2011succeeded in transmitting 26 terabits per second on a single laser beam. A "bit" is the smallest unit of information (a "0" or a "1"). That number is:

26 terabits = 26 000 000 000 000 = 2.6 × 10¹² bits

This is the equivalent of being able to transmit 700 DVDs per second!

Example 4

(7 × 10¹¹) × (6 × 10^-3)

= 42 × 10⁸ (This is not in scientific notation!)

= 4.2 × 10⁹

Exercises

Perform the following calculations using a calculator, by first expressing all numbers in scientific notation:

(1) 0.000 058 × 4 000 000 000

Answer

(2) 35 000 000 000 ÷ 0.000 000 000 000 07

Answer

35 000 000 000 ÷ 0.000 000 000 000 07

= (3.5 × 10¹⁰) ÷ (7 × 10⁻¹⁴)

= 5 × 10²³

[Note that a large number divided by a small number gives a very large number!]

(3) 0.000 000 000 000 06 ÷ 53 000 000 000 000

Answer

0.000 000 000 000 06 ÷ 53 000 000 000 000

= (6 × 10⁻¹⁴) ÷ (5.3 × 10¹³)

= 1.13207547 × 10⁻²⁷

[Considering the number of significant digits in the question, strictly our answer should be: 1 × 10⁻²³. Note also that a small number divided by a big number is a very small number.]