Standard
Form
What is it?
Why is it useful?
Standard Form
 Normal
numbers are easy to deal
with, we’re good at it
 Sometimes we get numbers that are
very very big or very very small.
These can be difficult to use with
normal numbers as you end up with
so many zeroes.
It’s easy to make a mistake.
Big Numbers
The speed of light is 300 million metres
per second, or 300 000 000 m/s
 This equates to twenty five thousand, nine
hundred and twenty million kilometres per
day, or 25 920 000 000 km/day
 When you hear light years on TV, it means
the distance that light travels in one year.
That’s 946 080 000 000 kilometres in one
year!

Tiny Numbers
Human hair
 Dust mite
 Lymphocyte
 Red blood cell
 E. Coli
 Staphylococcus
 Ebola virus

100 micrometres
200 micrometres
10 micrometres
5 micrometres
2 micrometres
0.5 micrometres
1000 nanometres
Tiny Numbers
Human hair
 Dust mite
 Lymphocyte
 Red blood cell
 E. Coli
 Staphylococcus
 Ebola virus

0.0001 m
200 micrometres
10 micrometres
5 micrometres
2 micrometres
0.5 micrometres
1000 nanometres
Tiny Numbers
Human hair
 Dust mite
 Lymphocyte
 Red blood cell
 E. Coli
 Staphylococcus
 Ebola virus

0.0001 m
0.0002 m
10 micrometres
5 micrometres
2 micrometres
0.5 micrometres
1000 nanometres
Tiny Numbers
Human hair
 Dust mite
 Lymphocyte
 Red blood cell
 E. Coli
 Staphylococcus
 Ebola virus

0.0001 m
0.0002 m
0.00001 m
5 micrometres
2 micrometres
0.5 micrometres
1000 nanometres
Tiny Numbers
Human hair
 Dust mite
 Lymphocyte
 Red blood cell
 E. Coli
 Staphylococcus
 Ebola virus

0.0001 m
0.0002 m
0.00001 m
0.000005 m
2 micrometres
0.5 micrometres
1000 nanometres
Tiny Numbers
Human hair
 Dust mite
 Lymphocyte
 Red blood cell
 E. Coli
 Staphylococcus
 Ebola virus

0.0001 m
0.0002 m
0.00001 m
0.000005 m
0.000002 m
0.5 micrometres
1000 nanometres
Tiny Numbers
Human hair
 Dust mite
 Lymphocyte
 Red blood cell
 E. Coli
 Staphylococcus
 Ebola virus

0.0001 m
0.0002 m
0.00001 m
0.000005 m
0.000002 m
0.0000005 m
1000 nanometres
Tiny Numbers
Human hair
 Dust mite
 Lymphocyte
 Red blood cell
 E. Coli
 Staphylococcus
 Ebola virus

0.0001 m
0.0002 m
0.00001 m
0.000005 m
0.000002 m
0.0000005 m
0.000001 m
Standard Form

Example:
Express a light year in standard form
Light year = 946 080 000 000 km

Example:
Express the length of a single Ebola virus
in standard form
Ebola virus = 0.000001 m
Switching from Standard Form to
normal numbers
We also need to be able to switch
numbers in standard form to normal
numbers. How?
 Example:
An adult has 2.5 x 1013 red blood cells in
their body. Express this as a normal
number.
 Example:
The weight of a single grain of rice is 2.5 x
10-5 kg. Express this as a normal number.

Calculating with Standard Form

In addition to what we learned last week,
we often have to do calculations with
numbers that are in standard form.
Calculating with Standard Form

Example:
An adult typically has around
2.5 x 1013 red blood cells at any one
time. If they measure 5 x 10-6 m in
diameter, how far would they stretch
if laid end to end?
First things first, is it multiply or divide?
Calculating with Standard Form

Example:
A typical helping of rice weighs
4.5 x 10-2 kg. If a typical grain of rice
weighs 2.5 x 10-5 kg, how many
grains of rice are there in a typical
helping?
First things first, is it multiply or divide?