Most of the world uses the decimalized metric system which is officially called the "International System of Units". SI units include:
- Length - metre
- Mass - kilogram
- Capacity - litre
Prefixes used at the beginning of each of these units are shown in the table.
|LATIN PREFIXES FOR SMALLER UNITS|
|nano-||1 billionth OR 1/ 1 000 000 000|
|micro-||1 millionth OR 1/ 1 000 000|
|milli-||1 thousandth OR 1/ 1000|
|centi-||1 hundredth OR 1/ 100|
|GREEK PREFIXES FOR LARGER UNITS|
|kilo-||1 thousand OR 1000|
|mega-||1 million OR 1 000 000|
|giga-||1 billion OR 1 000 000 000|
Did You Know That...?
The metre was originally defined as the distance between the North Pole and the Equator divided by ten million. Now it is defined as the distance light travels in a vacuum in 1/ 299 792 458 parts of a second.
Converting Length Units
|LENGTH RULES||CONVERTING LENGTH UNITS|
|10 millimetres = 1 centimetre
1000 millimetres = 1 metre
100 centimetres = 1 metre
1000 metres = 1 kilometre
|When converting from large unit to a small unit, you multiply.
When converting from a small unit to a large unit, you divide.
Examples One - Converting from Large to Small Units
Q1. 5 km = m
Q2. 3.5 m = cm
Q3. 34.6 cm = mm
Examples Two - Converting from Small to Large Units
Q4. 6500 m = km
Q5. 43.8 cm = m
Q6. 3192 mm = m
Complete these length conversions.
Q1. 64.7 km = m
Q2. 63 m = km
Q3. 0.4 m = cm
Q4. 8.4 mm = cm
Q5. 0.9 km = mm
What is the Difference between Perimeter, Area and Volume?
In the word perimeter, "peri" means "around" and "meter" means "measure". Therefore, to find the perimeter is to measure around the boundary of an object. Perimeter is measured in metres. Examples where Perimeter is calculated are the length of:
- a fence around a farm
- a frame around a picture
- garden edging around a garden
- guttering around a house
- cornice around the ceiling of a room
Area is the flat or two dimensional size of an object. Area is measured in square metres (m2). Examples include the Area to:
- make clothes from fabric
- paint a wall
- tile a floor
- work out the cost of glass window panes
- make curtains
- lay turf (grass)
- spread fertilizer on a garden
Volume is the solid or space inside or the three-dimensional size of an object. Volume is measured in cubic metres (m3). If gas or liquid is measured, it is called capacity and is measured in litres. Examples where Volume or Capacity is used include the amount of:
- rock in a quarry
- plastic in a plumbing pipe
- concrete slabs
- air in a room (air-conditioning)
- gas in a barbecue gas bottle
- gasoline (petrol) in a car's tank
- milk in a carton
- water in a rainwater tank or a swimming pool
Maths Fun - How Far Does Chocolate Travel?
When you last ate chocolate, did you consider how far the main ingredients - cocoa, sugar, palm oil and vanilla - have travelled to get to your mouth? Brown Cocoa Solids from the cacao tree are primarily grown in Ivory Coast in Africa; Sugar from sugar cane comes mainly from Brazil; Palm Oil is a major export of Indonesia; and Vanilla (the second most expensive flavouring in the world after saffron) is also predominantly cultivated in Indonesia. Use an atlas to estimate the "food miles" or "food kilometres" that these ingredients travelled from the plants to your mouth.