How_To_Be_Good_At_Math

60 NUMBERS •^ COMPARING AND ORDERING DECIMALS

Comparing and

ordering decimals

When we compare or order decimals, we use what we know about

place value, just as we do when we compare whole numbers.

0.1 is greater than 0.01

The digits in the ones column are

the same, so we compare the digits in

the tenths column to find that 0.1 is the

greater number.

Ordering decimals

On page 22, we found out

how to put whole numbers

in order. Ordering decimals

works in just the same way!

Let’s help sun-loving Kloog choose a holiday

hotspot by putting his list of cities in order, with

the highest temperature first. As with whole

numbers, we order decimal numbers by

comparing their significant digits.

To find the greatest number, we compare each

number’s most significant digit. If they are the

same, we look at the second digits, and then, if

necessary, the third, and so on. We carry on

comparing until we have ordered the numbers.

.

.

O

0

0

1

0 1

Comparing

decimals

When we compare

decimals, we compare

the digits with the

highest place value

first to decide which

number is larger.

The

placeholder,

zero, tells

us there are

no tenths

5 is greater

than 1 so

2.65 is the

larger number

.

.

.

.

.

O 9 9 5 5 4

3

1

0

6

6

1

3

1

7

1

T 2 2 2 1 1

We compare the digits

in order, starting with

the most significant

New York 25.01

Sydney

15.67

Athens

29.31

Capetown 14.61

Cairo

29.13

CITY TEMP °C

July temperatures

Athens

Cairo

New York

Sydney

Capetown

.

.

O

2

2

6

6

1

5

2.65 is greater than 2.61

This time we have to compare

the hundredths columns to find

that the greater number of the

two is 2.65.

When we compare

decimals, we look at the

digits with the highest

place values first.

10

1

100

1

10

1

100

1

10

1 1001

060-061_Comparing_Ordering_Decimals.indd 60 29/02/2016 14:52