Cambridge International Mathematics

192 Mensuration (length and area) (Chapter 9)

Important units that you should be familiar with include:

Measurement of Standard unit What it means

Length metre How long or how far.

Mass kilogram How heavy an object is.

Capacity litre How much liquid or gas is contained.

Time hours, minutes, seconds How long it takes.

Temperature degrees Celsius and Fahrenheit How hot or cold.

Speed metres per second (m/s) How fast it is travelling.

The SI uses prefixes to indicate an increase or decrease in the size of a unit.

Prefix Symbol Meaning Prefix Symbol Meaning

terra T 1 000 000 000 000 centi c 0 : 01

giga G 1 000 000 000 milli m 0 : 001

mega M 1 000 000 micro ¹ 0 :000 001

kilo k 1000 nano n 0 :000 000 001

hecto h 100 pico p 0 :000 000 000 001

In this course we will work primarily with the prefixes kilo, centi and milli.

The base unit of length in the SI is themetre(m). Other units of length based on the metre are:

² millimetres(mm) used to measure the length of a bee

² centimetres(cm) used to measure the width of your desk

² kilometres(km) used to measure the distance between two cities.

The table below summarises the connection between these units of length:

1 kilometre(km)= 1000metres(m)

1 metre(m)= 100centimetres

1 centimetre(cm)=10millimetres(mm)

LENGTH UNITS CONVERSIONS

So, to convert cm

into km we ¥ 100

and then¥ 1000.

Notice that, when converting from:

² smaller units to larger units wedivideby the conversion factor

² larger units to smaller units wemultiplyby the conversion factor.

A LENGTH [6.1]

km m cm mm

̧100

́100

̧10

́1000 ́10

̧1000

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100 100
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100 100
Y:\HAESE\IGCSE01\IG01_09\192IGCSE01_09.CDR Tuesday, 23 September 2008 9:47:17 AM PETER