Selina solutions concise mathematics class 6 icse Solutions for Chapter 8 hcf and lcm

Exercises in Chapter 8 hcf and lcm Grade 6

Exercise 8(A)

Exercise 8(B)

Exercise 8(C)

Revision Exercise

Questions in Exercise 8(A)

Choose the correct answer for all the factors of 84.

Choose the correct answer for all the factors of 48.

Choose all the factors of 55.

Choose the correct answer for all the factors of 36.

Choose all the factors of 15.

Q1) Write all the factors of :

(i) 15

(ii) 55

(iii) 48

(iv) 36

(v) 84

Write all prime numbers less than 25.

Write all prime numbers between 15 and 35.

Q2) Write all prime numbers :

(i) less than 25

(ii) between 15 and 35

(iii) between 8 and 76

Write all prime numbers between 8 and 76.

Q3) Write the prime-numbers from :

(i) 5 to 45

(ii) 2 to 32

(iii) 8 to 48

(iv) 9 to 59

Q4) Write the prime factors of:

(i) 16

(ii) 27

(iii) 35

(iv) 49

Q5) If $P_n$ means prime factors of n, find:

$\left(i\right)\ P_6\ \ \left(ii\right)\ P_{24}\ \ \left(iii\right)\ P_{50}$

Questions in Exercise 8(B)

Q1) 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

Q2) 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

Q3) 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

Q4) 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

Q5) Find the greatest number that divides each of 180, 225 and 315 completely.

Q6) Show that 45 and 56 are co-prime numbers.

Q7) Out of 15, 16, 21 and 28, find out all the pairs of co-prime numbers.

Q8) Find the greatest no. that will divide 93, 111 and 129, leaving remainder 3 in each case.

Questions in Exercise 8(C)

Q1) 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

Q2) 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

Q3) 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.

Q4) The product of two numbers is 432 and their L.C.M. is 72. Find their H.C.F.

Q5) The product of two numbers is 19,200 and their H.C.F. is 40. Find their L.C.M.

Q6) Find the smallest number which, when divided by 12, 15, 18, 24 and 36 leaves no remainder

Q7) Find the smallest number which, when increased by one is exactly divisible by 12, 18, 24, 32 and 40

Q8) Find the smallest number which, when increased by one is exactly divisible by 12, 18, 24, 32 and 40

Questions in Revision Exercise

Q1) Find the H.C.F. of :

(i) 108, 288 and 420

(ii) 36, 54 and 138

Q2) Find the L.C.M. of:

(i) 72, 80 and 252

(ii) 48, 66 and 120

Q3) 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.

Q4) The product of two numbers is 12096 and their H.C.F. is 36. Find their L.C.M.

Q5) 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.

Q6) (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.

Q7) 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.

Q8) 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.

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Chapters in this book

Number System (Consolidating the Sense of Numberness)

Estimation

Numbers in India and International System (With Comparison)

Place Value

Natural Numbers and Whole Numbers (Including Patterns)

Negative Numbers and Integers

Number Line

HCF and LCM

Playing with Numbers

Sets

Ratio

Proportion (Including Word Problems)

Unitary Method

Fractions

Decimal Fractions

Percent (Percentage)

Idea of Speed, Distance and Time

Fundamental Concepts (Algebra)

Fundamental Operations (Related to Algebraic Expressions)

Substitution (Including Use of Brackets as Grouping Symbols)

Framing Algebraic Expressions (Including Evaluation)

Simple (Linear) Equations (Including Word Problems)

Fundamental Concepts (Geometry)

Angles (With their Types)

Properties of Angles and Lines (Including Parallel Lines)

Triangles (Including Types, Properties and Construction)

Quadrilateral

Polygons

The Circle

Revision Exercise on Symmetry (Including Constructions on Symmetry)

Recognition of Solids

Perimeter and Area of Plane Figures

Data Handling (Including Pictograph and Bar Graph)

Mean and Median