Unit 6: Measurement
Topic B: The Prefixes
The metric system uses the base units gram, metre, and litre. It would not be practical to use only the base units because sometimes the unit would be far too large and other times it would be too small.
- If your weight was written in grams, it might be 60000 g – that sounds massive!
- The distance from Vancouver to Montreal is approximately 4800000 m.
- To measure a sewing seam or to select a wrench using only metres would mean using decimal amounts such as 0.007 m for a wrench and 0.015 m for the seam allowance on a dress.
These measures would all be correct but inconvenient to use. They would be easier to understand as:
- Your weight is 60 kg.
- The distance from Vancouver to Montreal is approximately 4800 km.
- A 7 mm wrench and 1.5 cm for a seam allowance.
The metric prefixes are similar to the place values in our number system. The prefix in front of a base unit tells how many of the base unit. Each prefix can be combined with almost any unit.
You will need to memorize the most common prefixes, their symbols, and their meaning.
In our everyday life and studies, we use only a few of these prefixes. However, it is interesting to look at the pattern of the prefixes and compare their pattern to the place value that you know so well.
The ones to memorize are marked with an *.
| Prefix | Symbol | Number of Base Units |
|---|---|---|
| terra | T | 1000000000000 |
| giga | G | 1000000000 |
| mega | M | 1000000 |
| kilo* | k | 1000 |
| hecto* | h | 100 |
| deca* | da | 10 |
| no prefix | base | 1 |
| deci* | d | 0.1 |
| centi* | c | 0.01 |
| milli* | m | 0.001 |
| micro | μ | 0.000001 |
| nano | n | 0.000000001 |
| pico | o | 0.000000000001 |
Exercise 1
Use the Prefix Chart to answer these questions.
- Give the meaning and symbol for deca. Deca means ten base units.
- Give the meaning and symbol for hecto.
- Give the meaning and symbol for kilo.
- Write the symbols for these units: metre, gram, litre
- Look at the prefixes deci, centi, milli, (and also micro, nano, pico). These prefixes tell you that the measurement is less than the base unit; they give a fraction of the base unit.
- deci means: one tenth of the unit
- centi means:
- milli means:
As a memory helper, notice that these three units which give a fraction of the base unit, all end with the letter i. You already know that centi is the Latin word for one-hundredth, and that one cent is one hundredth of a dollar.
- Prefixes have been combined with base units in this exercise. Write the meaning and the symbol. The first two questions are done as examples.
- centimetre: one hundredth of a metre, cm
- decagram: ten grams, dag
- kilogram:
- hectometre:
- millilitre:
- kilometre:
- hectolitre:
- decametre:
Answers to Exercise 1
- deca means ten base units. da
- hecto means 100 base units. h
- kilo means 1000 base units. k
- metre m gram g litre. L
-
- deci means one tenth of the unit
- centi means one-hundredth of the unit
- milli means one thousandth of the unit
-
- one hundredth of a metre cm
- ten grams dag
- thousand grams kg
- hundred metres hm
- one-thousandth of a litre mL
- thousand metres km
- hundred litres hL
- ten metres dam
Exercise 2
| Symbol | Word Name | Meaning | Measures |
|---|---|---|---|
| kL | kilolitre | one thousand litres | capacity |
| hm | hectometre | one hundred metres | distance |
| dg | decigram | one tenth of a gram | mass |
| mm | |||
| daL | |||
| kg | |||
| m | |||
| mL | |||
| dag | |||
| cL | |||
| cm | |||
| hL | |||
| hg |
Answers to Exercise 2
| Symbol | Word Name | Meaning | Measures |
|---|---|---|---|
| kL | kilolitre | one thousand litres | capacity |
| hm | hectometre | one hundred metres | distance |
| dg | decigram | one tenth of a gram | mass |
| mm | millimetre | one-thousandth of a metre | distance |
| daL | decalitre | ten litres | capacity |
| kg | kilogram | thousand grams | mass |
| m | metre | one metre | distance |
| mL | millilitre | one thousandth of a litre | capacity |
| dag | decagram | ten grams | mass |
| cL | centilitre | one hundredth of a litre | capacity |
| cm | centimetre | one hundredth of a metre | distance |
| hL | hectolitre | hundred litres | capacity |
| hg | hectogram | hundred grams | mass |
We understand numbers by the way the digits (numerals) are arranged in relationship to each other and to the decimal point. Each position has a certain value. Our number system is a decimal system. The place value is based on ten.