Form One - Decimals Form One

8/3/2019 Form One - Decimals Form One

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MATHEMATICSMATHEMATICS

FORM 1FORM 1

MATHEMATICSMATHEMATICS

FORM 1FORM 1

DECIMALSDECIMALS

Created By: Sepang District Group



Learning outcomes:

Represent fractions 1/10 and 1/100 as a

decimals and vice-versa

Represent fractions with denominators 10,100 1000 as decimals.

Read and write decimals to thousandths.

Change fractions to decimals and vice-versa

Decimals and Fractions



INTRODUCTION

4.123kg



RELATIONSHIP BETWEEN

DECIMALS AND FRACTIONS

101=

The part is one part out of ten parts

= 0.1

1 0

1.0

0.110

0 0

Represent fractions as decimals



RELATIONSHIP BETWEEN

DECIMALS AND FRACTIONS

100

13=

The part is thirteen parts out of one hundred parts

=

0.13

10 .0

13.0

00.13

1003 003 00

0 00



Represent fractions with denominators 10, 100,

1000.

Decimals

Fractions10

1

100

1

1000

1

0.1 0.0010.01



Read and write decimals up to

thousandths.

0 4 7.

Zero point sevenfour



5 8.3

2

Three eightpoint five two



38.74Thirty-eight point seven four



CHANGE FRACTIONS TO

DECIMALS

4

3 = 3 ÷ 475.0

00.34

2 80

2020

00= 0.75

RULE: Divide the numerator by the denominator.



TRY!

5

2= 0.4



CHANGE DECIMALS TO

FRACTIONS

RULE : Express the decimal as a fraction by using 10, 100,

1000 and so on, as the denominator of the fraction.

5

20.4

2

= =10

45

4 ÷ 2

10 ÷ 2



0.05 =20

1

TRY!



Place Value and Value of Each Digit in

Decimals

Learning Outcomes:

State the place value and value of each in decimals.

Compare the values of two given decimals.

Arrange decimals in order.

Round decimals to the nearest whole number up to three

decimal places.



PLACE VALUE AND VALUE OF

EACH DIGIT IN DECIMALS

.

Place value

Tens Units - Tenths Hundredths Thousandths

value -

Decimalplace

4 5 . 8 6 2

40 5 0.8 0.06 0.002

1st 2nd 3rd

4 5 8 6 2



TRY!

81.654State the place value of the underlined digit

State the value of the underlined digit

Hundredths

0.05



Arrange 2.5, 2.05, 2.53, and

2.505 in increasing order

2.5 =2.500

2.05 = 2.0502.53= 2.5302.505= 2.5050

2.05 2.5, ,2.505 ,2.53The decimals have arranged in

increasing order



Round off 14.78

to the nearest whole number

4 . 7 8

The first digit on the right is greater than 5

+1

Add I to digit 4

1 5

Drop all the decimals



Round off 5.316 to 1 decimal place

5 . 3 1 6

Underline digit 3

(1st decimal place).

The first digit on the right

is less than 5

Do not

change digit 3

Drop all the digits

to the right 3



Round off 4.387 to 2 decimal places

4 . 3 8 7

Underline digit 8

(2nd

decimal place).

The first digit on the right

is more than 5

Add 1 to 8

9

+1



TRY!34.561

1) To the nearest whole number

2) To 1 decimal place

3) To 2 decimal places

3534.6

34.56



Addition and Subtractions of Decimals

Learning Outcomes:

Add decimals

Solve problems involving addition of decimals.

Subtract decimals.

Solve problems involving subtraction of decimals



ADDITION OF DECIMALS

34.571 + 21.332 =

34 . 5 17

33.12 2+ 09.55 3

1

55.903



10.345+112.3+8.61=

12 . 3 00

16.8 0+ 52.13

1

131.255

1 .0 431

5

1

1 5



SUBTRACTION OF DECIMALS

64.718 - 21.404 =

64 . 7 8104.12 4-13.34 4

1

43.314



10.345 - 2.83 =

2 . 8 03-

15.7 5

13

7.515

1 .0 43 5

90



Multiplication and Division

of Decimals

Learning Outcomes:

Multiply two or more decimals

Solve problems involving multiplications of

decimals

Divide

A decimals by a whole Number



Multiplying Two or More

Decimals

Mentally multiply decimals by 10

1.746 x 10 =1 7 4 6

Shift the decimal point one place to the right.




1.746 x 100 =1 7 4 6

Shift the decimal point two places to the right.




1.746 x 1000 =1 7 4 6

Shift the decimal point three places to the right.



Mentally multiply decimals by 0.1

17.5 x 0.1 = 1 7 5

Shift the decimal point one place to the left.




17.5 x 0.01 1 7 5

Shift the decimal point two places to the left.

0=




17.5 x 0.001 1 7 5Shift the decimal point three places to the left.

= 00



8 4 2 x 7 =

8 4 2

x 7

5 8 9 4

two decimal places

two decimal places

5 8 9 4



1 9 x 3 =

1 1 9

x 5

55

9 5

one decimal place

one decimal place

1 5

3

3 75614

14 6 5



1 9 x 3 =

1 1 9

x5

55

9 5

one decimal place

one decimal place

1 5

3

3 7

5614

14 6 5

two decimal places



1 9 x 3 =

1 1 9

x

5

55

9 5

1 5

3

3 7

5614

14 6 5

one decimal place

one decimal place

three decimal places

0

0



Mentally divide decimals by 10

705.3 ÷ 10 7 0 5

Shift the decimal point one place to the left.

= 3

Dividing Decimals By

Whole Number




705.3 ÷ 100 7 0 5Shift the decimal point two places to the left.

= 3




705.3 ÷ 1000 7 0 5

Shift the decimal point three places to the left.

= 30



35 ÷ 0.4

= 350.4

= 35 x 10

0.4 x 10= 350

4= 87.5

Multiply the numerator

And denominator by 10

to change the denominatorto a whole number



9 ÷ 3.12

= 93.12

= 9 x 100

3.12 x 100= 900

312= 2.8846

Multiply the numerator

and denominator by 100

to change the denominatorto a whole number

Documents

Form One - Decimals Form One