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 non-zero 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
- 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) 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
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= √(32 x 52 x 72)= 3 X 5 X 7=105
Example
Find the square roots of √54/9
Solution:
√54/9 =√49/9=√49/√9=7/3=2 1/3
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
- 45.34672 to 2 d.p. is ______
See also
H.C.F & L.C.M AND PERFECT SQUARES
WHOLE NUMBERS AND DECIMAL NUMBERS