Page 32 - Mathematics Coursebook

3 Place value, ordering and rounding

!e decimal system is a number system based on 10. All the Key words
numbers can be written by using just the ten digits 0, 1, 2, 3, 4, 5, 6,
7, 8 and 9. Make sure you learn and

!e world’s earliest decimal system used lines to represent numbers, understand these key words:
so their digits 1 to 9 looked something like this. decimal number
decimal point
1 2 3 4 5 decimal places
place-value table
round
6 7 8 9
approximate
short division
estimate
Before the symbol for zero (0) was invented, people used a blank inverse operation
space to represent it.
Many countries in the world use a decimal system for their currency,
where each unit of currency is based on a multiple of 10.

For example:
UK, 1 pound = 100 pence (£1 = 100p)
Europe, 1 euro = 100 cents (€1 = 100c)
USA, 1 dollar = 100 cents ($1 = 100c)
Gambia, 1 dalasi = 100 bututs

China, 1 yuan = 100 fen

!ailand, 1 baht = 100 satang
When you travel to di#erent countries you need to use

di#erent currencies. It is easier to understand new currencies
if they are based, like your own, on the decimal system.
In this unit you will learn more about understanding and using
decimal numbers.

3 P lace v alue, or dering and r ounding 31
3 Place value, ordering and rounding