Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM

Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM

Selina Publishers Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM

HCF and LCM Exercise 8A – Selina Concise Mathematics Class 6 ICSE Solutions

Question 1.
Write all the factors of :
(i) 15
(ii) 55
(iii) 48
(iv) 36
(v) 84
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8A 1

Question 2.
Write all prime numbers :
(i) less than 25
(ii) between 15 and 35
(iii) between 8 and 76
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8A 2

Question 3.
Write the prime-numbers from :
(i) 5 to 45
(ii) 2 to 32
(iii) 8 to 48
(iv) 9 to 59
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8A 3

Question 4.
Write the prime factors of:
(i) 16
(ii) 27
(iii) 35
(iv) 49
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8A 4

Question 5.
If Pn means prime factors of n, find:
(i) p6
(ii) P24
(iii) p50
(iv) P42
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8A 5

HCF and LCM Exercise 8B – Selina Concise Mathematics Class 6 ICSE Solutions

Question 1.
Using the common factor method, find the H.C.F. of :
(i) 16 and 35
(ii) 25 and 20
(iii) 27 and 75
(iv) 8, 12 and 18
(v) 24, 36, 45 and 60
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 6

Question 2.
Using the prime factor method, find the H.C.F. of:
(i) 5 and 8
(ii) 24 and 49
(iii) 40, 60 and 80
(iv) 48, 84 and 88
(v) 12, 16 and 28
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 7

Question 3.
Using the division method, find the H.C.F. of the following :
(i) 16 and 24
(ii) 18 and 30
(iii) 7, 14 and 24
(iv) 70,80,120 and 150
(v) 32, 56 and 46
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 8
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 9
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 10

Question 4.
Use a method of your own choice to find the H.C.F. of :
(i) 45, 75 and 135
(ii) 48, 36 and 96
(iii) 66, 33 and 132
(iv) 24, 36, 60 and 132
(v) 30, 60, 90 and 105
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 11
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 12

Question 5.
Find the greatest number that divides each of 180, 225 and 315 completely.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 13

Question 6.
Show that 45 and 56 are co-prime numbers.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 14

Question 7.
Out of 15, 16, 21 and 28, find out all the pairs of co-prime numbers.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 15
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 16

Question 8.
Find the greatest no. that will divide 93, 111 and 129, leaving remainder 3 in each case.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8B 17

HCF and LCM Exercise 8C – Selina Concise Mathematics Class 6 ICSE Solutions

Question 1.
Using the common multiple method, find the L.C.M. of the following :
(i) 8, 12 and 24
(ii) 10, 15 and 20
(iii) 3, 6, 9 and 12
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 18

Question 2.
Find the L.C.M. of each the following groups of numbers, using
(i) the prime factor method and
(ii) the common division method :
(i) 18, 24 and 96
(ii) 100, 150 and 200
(iii) 14, 21 and 98
(iv) 22, 121 and 33
(v) 34, 85 and 51
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 19
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 20
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 21

Question 3.
The H.C.F. and the L.C.M. of two numbers are 50 and 300 respectively. If one of the numbers is 150, find the other one.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 22

Question 4.
The product of two numbers is 432 and their L.C.M. is 72. Find their H.C.F.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 23

Question 5.
The product of two numbers is 19,200 and their H.C.F. is 40. Find their L.C.M.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 24

Question 6.
Find the smallest number which, when divided by 12, 15, 18, 24 and 36 leaves no remainder
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 25

Question 7.
Find the smallest number which, when increased by one is exactly divisible by 12, 18, 24, 32 and 40
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 26

Question 8.
Find the smallest number which, on being decreased by 3, is completely divisible by 18, 36, 32 and 27.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Ex 8C 27

HCF and LCM Revision Exercise – Selina Concise Mathematics Class 6 ICSE Solutions

Question 1.
Find the H.C.F. of :
(i) 108, 288 and 420
(ii) 36, 54 and 138
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Revision Ex 28

Question 2.
Find the L.C.M. of:
(i) 72, 80 and 252
(ii) 48, 66 and 120
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Revision Ex 29

Question 3.
State true or false : Give an example.
(i) H.C.F. of two prime numbers is 1.
(ii) H.C.F. of two co-prime numbers is 1.
(iii) L.C.M. of two prime numbers is equal to their product.
(iv) L.C.M. of two co-prime numbers is equal to their product.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Revision Ex 30

Question 4.
The product of two numbers is 12096 and their H.C.F. is 36. Find their L.C.M.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Revision Ex 31

Question 5.
The product of the H.C.F. and the L.C.M. of two numbers is 1152. If one number is 48, find the other one.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Revision Ex 32

Question 6.
(i) Find the smallest number that is completely divisible by 28 and 42.
(ii) Find the largest number that can divide 28 and 42 completely.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Revision Ex 33

Question 7.
Find the L.C.M. of 140 and 168. Use the L.C.M. obtained to find the H.C.F. of the given numbers.
Solution:
Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Revision Ex 34

Question 8.
Find the H.C.F. of 108 and 450 and use the H.C.F. obtained to find the L.C.M. of the given numbers.
Solution:
<Selina Concise Mathematics Class 6 ICSE Solutions Chapter 8 HCF and LCM Revision Ex 35

Selina Concise Mathematics Class 6 ICSE Solutions

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