Back to: MATHEMATICS JSS 2
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In today’s Mathematics class, We will be discussing Whole Numbers Decimal Numbers. We will also be looking at Multiples and Factors of Numbers. We hope you enjoy the class!
Content
 Whole Difference between Whole Numbers and Decimal Numbers
 Whole numbers in Standard Form and Decimal Numbers in Standard Form
 Factors, Multiples and Prime Numbers
Difference between Whole Numbers and Decimal Numbers
A whole number is a number without fraction. For example 1, 2, 3, 4…1000, 38888 are examples of whole numbers. 71/2 is not a whole number. A decimal number is a fractional number less than 1. It is smaller to a whole number. Examples – 0.1, 0.01, 0.001etc
Whole Numbers in Standard Form and Decimal Numbers in Standard Form
Whole numbers in standard form are expressed in the form of A x 10^{n} such that A is a number between 1 and 10, n is a whole number.
Example
Express the following in standard form (a) 200 (b) 4100 (c) 300000
Solution
 200 = 2 x 100 = 2×10^{2}
 4100 = 4.1 x 1000 = 4.1 x 10^{3}
 300000 = 3 x 100000 = 3 x 10^{5}
Evaluation
Express the following in standard form (a) 500 (b) 36000 (c) 7200000
Decimal fractions such as 0.00 and 0.000001 can be expressed as powers of 10
e.g. 0.0001 = 1/10000 = 1/10^{4 }= 10^{4 }
Thus, any decimal fraction can be expressed in a standard form
e.g. 0.008= 8/1000= 8/10^{3 }= 8×1/10^{3 }= 8×10^{3}
Therefore, the number 8×10^{3 }is in standard form ax10 and n is a negative integer while A is a number between1 and 10
Example
Express the following in standard form (a) 0.0023 (b) 0.00034 (c) 0.125
Solution
 023 = 23/1000 = 2.3/10^{2} = 2.3 x 10^{3}
 00034 34/100000= 3.4/10^{4} = 3.4x 10^{4}
 125 = 125/1000 = 1.25/10^{1} = 1.25×10^{1}
Evaluation
Express the following in standard form (a) 0.0067 (b) 0.00082 (c) 0.012
READING ASSIGNMENT
New General Mathematics, UBE Edition, chapter 1, pages 2728
Essential Mathematics by A J S Oluwasanmi, Chapter 1, pages 14
FACTORS, MULTIPLES AND PRIME NUMBERS
The factors of a number are the whole numbers that divide the number exactly. For example, the factors of 10 are 1, 2 and 5.
A prime number has only two factors, itself and 1. The following are examples of prime numbers 2, 3, 5, 7, 11, 13…. However, 1 is not a prime number.
A multiple of a whole number is obtained by multiplying it by any whole number.
Example
 Write down all the factors of 18.
 State which of these factors are prime numbers
 Write the first three multiples of 18
 Express 18 as a product of its prime factors in index form
Solution:
 Factors of 18 are 1, 2,3,6,9 and 18.
 Prime numbers of the factors of 18 are 2 and3
 The first three multiples of 18 are 1×18 = 18, 2×18=36, 3×18=54 => 18, 36 and 54.
 18 = 2x3x3 = 2 x 3^{2} in index form
Example 2:
 Write down all the factors of 22.
 State which of these factors are prime numbers
 Write the first three multiples of 22
Solution:
 Factors of 22 are 1, 2, and 11.
 Prime numbers of the factors of 22 are 2 and11
 The first three multiples of 22 are 1×22 = 22, 2×22=44, 3 x 22=66 => 22, 44 and 66.
Evaluation
 Write down all the factors
 State which of these factors are prime numbers
 Write the first three multiples of each of the following numbers below
 Express each as a product of its prime factors in index form


 (A) 12 (B) 30 (C) 39 (D) 48

READING ASSIGNMENT
New General Mathematics, UBE Edition, Chapter, 1 page 1314
Essential Mathematics by A J S Oluwasanmi, Chapter 1, pages 14
WEEKEND ASSIGNMENT
 Which of these is not a prime number (a) 2 (b) 5 (c) 7 ( d) 1
 Express 360000 in standard form (a) 3.6 x 10^{5} (b) 3.6 x 10^{6} (c) 3.6 x 10^{3}^{ } (d) 3.6 x 10^{4}
 Express 0.000045 in standard form (a) 4.5 x 10^{2 }(b) 4.5 x 10^{3 }(c) 4.5 x 10^{5 }(d) 4.5 x 10^{6}
 Which of these is not a factor of 42 (a) 9 (b) 6 (c) 7 (d) 2
 Express 50 is product of its prime factor (a) 2 x 5^{2} (b) 2 x 5 (c) 2^{2 }x 5^{2} (d) 2 x 5
THEORY
 For each number 42,45,48,50
 Write down all its factors.
 State which factors are prime numbers?
 Express the number as a product of its prime factors.
 Express the following in standard form (a) 345000 (b) 0.00034 (c) 0.125
We have come to the end of this class. We do hope you enjoyed the class?
Should you have any further question, feel free to ask in the comment section below and trust us to respond as soon as possible.
In our next class, we will be talking about LCM, HCF and Perfect Squares. We are very much eager to meet you there.
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