Back to: MATHEMATICS JSS 2
Welcome to Class !!
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In today’s Mathematics class, We will be discussing “Approximation of Numbers”. We hope you enjoy the class!
APPROXIMATION OF NUMBERS ROUNDING OFF TO DECIMAL PLACES
Digits 1,2,34 are rounded down to Zero, while digits 5, 6, 7, 8, and 9 are rounded up to 1 e.g. 126=130 to 2 digits
A significant figure begins from the first nonzero digit at the left of a number. Digit should be written with their correct place values.
Worked example
 Round off the following to the nearest (i) Thousand (ii) hundred (ii) ten
(a) 8615 (b) 16,560
Solution
a.



 i) 8615 ≈ 9000 {to the nearest thousand}
 ii) 8615 ≈8600 {to the nearest hundred}
 iii) 8615 ≈8620 {to the nearest ten}


b.
(i) 16560≈17000 {to the nearest thousand}
(ii) 1660≈16, 600 {to the nearest hundred}
(iii) 16560 ≈16560 {to the nearest ten}
 Round off the following to the nearest (i) whole number (ii) tenth (iii) hundred
(a) 3.125 (b) 0.493
Solution
a.
(I) 3.125≈3 {to the nearest whole number}
(ii) 3.125≈3.1{to the nearest tenth}
(iii) 3.125≈3.13{to the nearest hundredth}
b.
(i) 0.493≈0 {to the nearest whole number}
(ii) 0.493≈0.5{to the nearest tenth}
(iii) 0.493≈0.49{to the nearest hundredth
Evaluation
Round off the following to a) p. (b) 2 d.p. (c) 3 d.p.
(1) 12.9348 (2) 5.0725 (3) 0.9002
Square Roots of Numbers
The symbol ‘√’ means “square root of”. To find the square root of a number, first, find its factors.
Examples
 Find the square root of 11025
Solution
(a) √11025
3  11025
3  3675
5  1225
5  245
7  49
7  7
√11025= √(3^{2} x 5^{2} x 7^{2})= 3 X 5 X 7=105
Example
Find the square roots of √49/9
Solution:
$\sqrt{\raisebox{1ex}{$49$}\!\left/ \!\raisebox{1ex}{$9$}\right.}=\frac{\sqrt{49}}{\sqrt{9}}=\frac{7}{3}=2\frac{1}{3}$
READING ASSIGNMENT
New General Mathematics, UBE Edition, Chapter 2, pages 2832, 2021
Essential Mathematics by A J S Oluwasanmi, Chapter 1, pages 4245
WEEKEND ASSIGNMENT
 What is 0.003867 to 3 significant figure (a)0.004 (b)0.00386 (c)0.00387 (d)386
 The square root of 121/2 is ____(a)1 3/4 (b)3 1/2 (c)3 3/4 (d)6 1/4
 9852 to 3 S.F. is _____(a)990 (b) 9850 (c) 9580 (d) 986
 7.0354 to 2 d.p is _____(a) 7.03(b) 7.04 (c) 7.40 (d)7.13
 59094 to the nearest hundred is ____(a) 59100(b)59104 (c) 60094 (d) 60194
THEORY
 Find the square root of 1296
 a. What is 0.046783 to 3 significant figure?
 b. 45.34672 to 2 d.p. is ______
We have come to the end of this class. We do hope you enjoyed the class?
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In our next class, we will be talking about Multiplication and Direction of Directed and Nondirected numbers. We are very much eager to meet you there.
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