Download DOWEN COLLEGE LAGOS

DOWEN COLLEGE LAGOS
ONLINE SCHOOL ACTIVITY
WEEK 2 LESSON JS2
Subject :mathematics
Topic : standard form
Definition: all numbers written in the form A x 10n where A is the
number between 1 and 10 and n is a whole number are called numbers
in standard form.
Standard forms are sometimes called scientific notation.
Numbers greater than 1
Example ( a ) 20000 = 2 x 10000 = 2 x 104
( b ) 450
= 4.5 x 100 = 4.5 x 102
( c ) 630000 = 6.3 x 100000 = 6.3 x 105
Task 1
Express the following numbers in standard form.
( I ) 8000 ( ii ) 170000 ( iii ) 950 ( iv ) 70 ( v ) 57
Numbers less than 1
Decimal fractions such as 0.001 and 0.000001 can be express as power
of 10 for example.
( 1 ) 0.00001 =
=
= 10 – 5
( 2 ) 0.0003 = =
=
= 3 x 10 – 4
DOWEN COLLEGE LAGOS
ONLINE SCHOOL ACTIVITY
( 3 ) 0.0026 =
= 2.6 x 10 – 3
=
Task 2
Express the following in standard form.
( I ) 0.0006 ( ii ) 0.06 ( iii ) 0.4 ( iv ) 0.0052 ( v) 0,066
Expressing numbers in decimal fraction
Example ( a ) 7 x 10 – 1 ( b ) 9.2 x 10 – 3 ( c ) 5.6 x 10 – 6
( a ) 7 x 10 – 1 =
( b ) 9.2 x 10 – 3 =
( c ) 5.6 x 10 – 6 =
= 0.7
= 0.0092
= 0.0000056
Addition and Subtraction in standard form
In order to add or subtract expressions in standard form, the powers of
10 must be made equal.
Example
( a ) 6.08 x 10 7 + 3.01 x 10 7 ( b ) 9.4 x 105 - 6.7 x 10 5 ( c ) 0.0065 +
0.003
( d ) 0.000006 - 0.0000024 ( e ) 2.5 x106 +5.3 x 106 – 3.4 x 106
Solution
DOWEN COLLEGE LAGOS
ONLINE SCHOOL ACTIVITY
( a ) 6.08 x 10 7 + 3.01 x 10 7 = ( 6.08 + 3.01 ) x 107 = 9.09 x 107 Since
107 is common
( b ) 9.4 x 105 - 6.7 x 10 5 = ( 9.4 - 6.7 ) x 105 = 2.7 x 105
( c ) 0.0065 + 0.003 = 6.5 x 103 + 3 x 103 = ( 6.5 + 3 ) x 103 = 9.5 x 103
(d ) 0.000006 - 0.0000024 = 6 x 10 – 6 - 2.4 x 10 – 6 = ( 6 – 2.4 ) x 10 – 6
( e ) 2.5 x 10 6 + 5.3 x 106 – 3.4 x 10 6 = ( 2.5 + 5.3 – 3.4 ) x 10 6
Multiplication and Division in Standard form
The process of multiplication and division follows similar rules as in
operation of indices.
e.g if P = A X 10x and Q = B x 10y
PQ = A X 10x X B x 10y = AB X 10 x + y
Also in division of P ÷ Q or
=
= X
= 10 x – y
Example
( a ) simplify ( 1.6 x 109 ) x ( 2.5 x 10 6 ) = ( 1.6 x 2.5 ) x 109 + 6 = 4 x 1015
( b ) 5.8 x 10 16 ÷ 1.4 x 1011 = ( 5.8 ÷ 1.4 ) x 10 16 – 11 = 4.143 x 10 5
DOWEN COLLEGE LAGOS
ONLINE SCHOOL ACTIVITY
ASSIGNMENT 1
New General Mathematics Book 2
( a ) Page 26 exercise 2e ( question 1, 8, 10, 21, 24 )
( b ) Page 27 exercise 2f ( question 1, 5, 11, 20, 24 )
( c ) Page 27/28 exercise 2g ( question 1, 2, 16, 17, 24 )
( d ) Page 26 exercise 2e ( question 1, 8, 14, 22, 24 )
ASSIGNMENT 2
( a ) simplify ( 2.5 x 109 ) x ( 3 x 104 )
( b ) simplify ( 4.6 x 108 ) ÷ ( 1.5 x 103 )
( c ) 4.2 x 106 + 2.1 x 106
( d ) 3.1 x 104 + 1.2 x 104 – 3.2 x 104
Kindly solve the tasks and assignment and forward the solution to:
[email protected] or [email protected]
(08025949100)
Submission should not be later than Wednesday 17th of September 2014.
NOTE : these will form part of your continuous assessment for first term.
DOWEN COLLEGE LAGOS
ONLINE SCHOOL ACTIVITY