Tuesday, 14 September 2021 13:10

# Numbers - Class 8 Mathematics Revision Notes

In this section you will need the following hints to solve the exercises:

• Place value of whole numbers
• Total value of whole numbers
• Multiplication of whole numbers/tables
• BODMAS
• LCM and GCD

Worked Exercise

1. What is four million seventy thousand and five hundred and thirty three?
1. 4,070,353
2. 4,070,533
3. 4,007,533
4. 4,700,533

Working
Using the place value table, the question can be solved as follows:
 Millions HundredThousands Tenthousands Thousands Hundreds tens Ones 4 0 7 0 5 3 3
The correct answer is B (4070533)
2. What is the square root of 7 9/16
1. 7 ¾
2. 2 ¾
3. 1 3/8
4. 21/16
Working
Step 1: Change the mixed fraction to improper Find the square root of both numerator and denominator.
Step 2: Find the square root of both numerator and denominator
= √121
√16
=11/4
Step 3: Change the improper fraction to mixed fraction
= 2¾
3. What is 25% as a fraction?
1. 1/5
2. ¾
3. ½
4. ¼
Working
Step1: Express the percentage with 100 as a denominator.
=25/100
Step 2: Simplify
4. What is the value of of 1/3 of(½ + 1/9) ÷1/6
1. 11/324
2. 1/99
3. 12/9
4. 4/11
Working
Step1: Using the order of operation, BODMAS, solve the brackets first.
1/2 + 1/9 = 11/18
Step 2: Open brackets and calculate ‘of ‘
=1/3 of (11/18) ÷ 1/6
=1/3 x (11/18) ÷ 1/6
=11/54 ÷ 1/6
Step3: Calculate the division part
=11/54 ÷ 1/6
=11/54 x 6/1(multiply by the reciprocal of 1/6)
=11/9
Step 4: Change the improper fraction to mixed fraction.
= 1 2/9
5. The price of radio is Sh1800. The price was reduced by 15% during an auction. How much is the price after the reduction?
1. Sh270
2. Sh2070
3. sh1530
4. sh1785
Working
Marked price = Sh1800
Percentage decrease = 15%
New price
85% of Sh1800 (100% - 15%)
= 85 x 1800/100
= Sh1, 530
The correct answer is Sh 1530 (C)
6. In a certain year a tea factory produced 2500 tonnes of tea leaves. The following year the tonnes increased to 4000. What is the percentage increase?
1. 160%
2. 62½ %
3. 60%
4. 37½ %
Working
First year = 2500 tonnes
Second year = 4000 tonnes
Increase = 1500 tonnes (4000-2500)
% Increase = Increase x 100/Original = 60%
The correct answer is C (60%)
7. What is the next number in the sequence below.
6, 10, 19, 35, …..
8. 60
9. 84
10. 71
11. 51
Working The next difference is 5² = 25
The next number is 35 + 25 = 60
The correct answer is A (60)