Page 92 - Math Smart - 7

CHAPTER 4.3
In this chapter

Pupils should be able to:
Tdering Decimals
• order decimals including
measurements,
in ascending and
descending order Scientists measure the magnitude
(strength) of earthquakes using
• change measurements
the Richter scale. The Richter scale
to the same units before
measures the magnitude of an
ordering them
earthquake on a scale of 1 to 10. The
Richter scale measures earthquakes
in decimal numbers to tenths. Most
earthquakes register 2.5 or less and
Which earthquake was the are too small to be noticed by people.
strongest? Earthquakes with a magnitude of 8.0
Look at the magnitude or higher on the Richter scale occur
of the following three about once every 5 to 10 years.
earthquakes. Work with
your partner to name the
4.3.1 Comparing and ordering
earthquakes in order from
the strongest (highest
decimals
magnitude) to the weakest
(lowest magnitude).
When you order any numbers, including decimals, you place them in order from:
• The Tohoku
earthquake (Japan
2011) had a Greatest to smallest Smallest to greatest
magnitude of 9.1 on (this is descending (this is ascending
the Richter Scale. order) order).
• TheValdivia
earthquake (Chile
1960) had a
Example 7
magnitude of 9.5 on
the Richter Scale.
Write these numbers in ascending order:
• The Prince William
Sound earthquake 1
6.45 6 4 5 Place-value tables are
(Alaska 1964) had a •
helpful when ordering
5.52 5
magnitude of 9.2 on • 5 2
decimals.
6.48
the Richter Scale. 6 • 4 S
5.68 5 • 6 8
In this example, all decimals begin with a digit in the units place.
In these decimals, the units have the highest place value.
You compare the units first.

The smallest value in the units place is 5.
5 <6.

UNIT 4 I Decimals