PLACE VALUES AND VALUES OF DECIMALS P.5

Write the place value and value of each digit in the No. below.

Values      (Note: Value = digit x place value)

What is the value of 8 in 0.238

0 . 2 3 8

8 x = = 0.008

Writing decimals in words.

i) 5 =

= Five tenths

ii) 8 One and eight tenths.

iii)     21.008

Twenty one and eight thousandths.

iv) 075

One hundred ninety five and seventy five thousandth.

Writing decimals in figures

Example

1)     Thirty six and four tenths

36     and

36 and 0.4                            

36.0

0.4

36.4

2)     Six tenth

= 0.6

3)     Fourteen hundredths

=      0.14

4)     One hundred twenty and fourteen hundredths.

120 and

120 and 0.14

Or

120.00

   0.14

120.14

EXPANDING WHOLE NUMBERS

Expanding using values

1)     Expand 349

349   =      (3 x 100) + (4 x 10) + (9 x 1)

300 +         40 + 9

2)     Expand 48914

48914 = (4 x 10,000) + (8 x 1000) + (9 x 100) + (1 x 10) + (4 x 1)

40,000       +       8000 +      900   +       10 +           4

Expanding using powers / exponents

148   =      1     4     8

10² 10¹ 10⁰

(1 x 10²) + (4 x10¹) + (8 x10⁰)

7 9 6 2      =      7      9      6      2

10³ 10²    10¹      10⁰

(7 x10³) + (9 x10²) + (6 x10¹) + (2 x 10⁰)

Writing expanded numbers as single numbers / short form.

What number has been expanded to give;

(2 x10³) + (4 x10²) + (3 x10¹) + (7 x 10⁰)

REFERENCE:      Mk bk 5, pg 31 – 32, MK Bk. 7 pg 48

                             Understanding Math bk 5, pg 21.

EXPANDING DECIMALS

1)     Using values

1. i) Expand 2 8 . 3 6 9

=      2      8 . 3          6      9

T              O        TTHS     HTHS  THS

=      (2 X 10) + (8 X 1) + (3 X) + (6 X ) + ()

20     +   8     +   0.3     +   0.06     + 0.009

1. ii) Expand 1 3 5 . 6 5

(1 X 100) + (3 X 10) + ( 5 x 1) + (6 X) + (7 X )

100 +   30       +   5       +   0.6     + 0.07

2. Using powers

Expand 28.369 using powers.

2        8        .         3        6        9

10¹      10⁰                 10^-1 10^-2   10^-3

(2 X10¹) + (8 X10⁰) + (3 X10^-1 ) + (6 X10^-2) + (9 x 10^-3)

Writing expanded decimals in their shortest form. Mk bk. 7, pg 48 – 49