Worksheet Solutions: Multiples & Factors | Mental Mathematics for Class 8 PDF Download

Q1: Answer the following question:
(i) Write first twelve multiples of 5.
Ans: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60

(ii) Is 1 a prime number or composite number?
Ans: 1 is neither a prime number nor a composite number.

(iii) Is there an even prime number?
Ans: Yes, 2 is an even prime number.

Q2: Fill in the blanks:
(i) 1 is a ________ number.
Ans: unique

(ii) The smallest composite number is ________.
Ans: 4

(iii) The smallest natural number is ________.
Ans: 1

(iv) The smallest whole number is ________.
Ans: 0

(v) The first 3 multiples of 12 are ________.
Ans: 12, 24, 36

(vi) 3, 7, 9, 15, 25 are ________ numbers.
Ans: odd

(vii) ________ is a factor of every number.
Ans: 1

(viii) ________ is a factor of every even number.
Ans: 2

(ix) A ________ number has only 2 factors one and the number itself.
Ans: prime

(x) A composite number has more than ________ factors.
Ans: two

(xi) The factors of 6 are ________.
Ans: 1, 2, 3, 6

(xii) A number is a factor of another number if on dividing the ________ is zero.
Ans: remainder

Q3: Find prime factors of the following:
(i) 786
Ans: 786 2, 3 and 131

(ii) 256
Ans: 2, 2, 2, 2, 2, 2, 2 and 2

(iii) 324
Ans: 2, 2, 3, 3, 3 and 3

(iv) 546
Ans: 2, 3, 7 and 13

(v) 484
Ans: 2, 2, 11 and 11

(vi) 117
Ans: 3, 3 and 13

Q4: Complete the given multiplication grid.
(i) Find all the multiples of 3 yellow.
Ans: 3 ,6, 9, 12, 18, 15, 21, 24, 27, 30, 33, 36, 42, 45, 48, 54, 60, 63, 66, 72, 81, 90, 99

(ii) Circle all the even numbers greater than 50 but less than 80.
Ans: 54, 56, 60, 66, 64, 70, 72.

(iii) Write first 5 multiples of 7, 8 and 11.
Ans: First 5 multiples of 7 are: 7, 14, 21, 28, 35.
First 5 multiples of 8 are: 8, 16, 24, 32, 40.
First 5 multiples of 11 are: 11, 22, 33, 44, 55.

(iv) Is 7 a factor of 35?
Ans: Yes, 7 is a factor of 35. [Since, 7 × 5 = 35]

(v) Is 11 a factor of 47?
Ans: 11 is not a factor of 47. [Since, 47 is not divisible by 11]

(vi) Is 9 a factor of 72?
Ans: Yes, 9 is a factor of 72. [Since, 9 × 8 = 72]

Q5: Which of the following numbers are prime:
(i) 2
(ii) 6
(iii) 11
(iv) 15
(v) 39
(vi) 93
(vii) 57
(viii) 75
(ix) 81
(x) 87
Ans: (i) 2 and (iii) 11

Q6: Write all the factors of:
(i) 18
Ans: 1, 2, 3, 6, 9, 18

(ii) 20
Ans: 1, 2, 4, 5, 10, 20

(iii) 14
Ans: 1, 2, 7, 14

(iv) 23
Ans: 1, 23

Q7: Find out if the first number is a factor of the second number.
(i) 15, 180
Ans: 15 is a factor of 180

(ii) 16, 112
Ans: 16 is a factor of 112

(iii) 22, 133
Ans: 22 is not a factor of 133

(iv) 25, 230
Ans: 25 is not a factor of 230