RBSE Class 6 Maths Important Questions Chapter 3 Playing With Numbers

Rajasthan Board RBSE Class 6 Maths Important Questions Chapter 3 Playing With Numbers Important Questions and Answers.

RBSE Class 6 Maths Chapter 3 Important Questions Playing With Numbers

Multiple Choice Questions

Question 1.
Which of the following number is a prime number?
(a) 23
(b) 42
(c) 52
(d) 36
Answer:
(a) 23

Question 2.
Which of the following is a composite number?
(a) 5
(b) 13
(c) 24
(d) 31
Answer:
(c) 24

Question 3.
The H.C.F. of two co-prime numbers is:
(a) 0
(b) 3
(c) 2 
(d) 1
Answer:
(d) 1

Question 4.
The L.C.M. of two consecutive numbers is equal to:
(a) Their sum
(b) Their product
(c) Their difference
(d) None of these
Answer:
(b) Their product

Question 5.
The smallest 4-digit number which is divisible by 6, 8, 9 :
(a) 2012
(b) 2160
(c) 2088
(d) 1008
Answer:
(d) 1008

Question 6.
The number of multiples of a given number is:
(a) 10
(b) 100
(c) 1000
(d) Infinite
Answer:
(d) Infinite

Fill in the Blanks

Question 1.
Every multiple of a given number is greater than or equal to that __________
Answer:
number

Question 2.
The number __________ is the smallest prime number and is even. 
Answer:
2

Question 3. 
The H.C.F. of two co-prime numbers is __________
Answer:
1

Question 4. 
If two numbers are divisible by a given number, then there __________   also __________ divisible by that number.
Answer:
sum

Question 5. 
A number is divisible by __________ if it is divisible by both 3 and 6.
Answer:
2.

Very Short Answer Type Question

Question 1. 
Can two numbers have 16 as their H.C.F. and 380 as their L.C.M.? Give, reasons.
Answer:
No. We know that H.C.F. of the given two numbers must exactly divide their L.C.M.
But 16 does not divide 380 exactly.
Hence, we cannot have two numbers with 16 as their H.C.F. and 380 as their L.C.M.

Short Answer Type Questions

Question 1. 
Telegraph pole occur at equal distances of 220 m along a road and heaps of stones are put at equal distances of300m along the same road. The first heap is at the foot of the first pole. How far from it along the road is the next heap which lies at the foot of a pole?
Answer:
We have to find the L.C.M. of 220 m and 300 m.
Prime factorisation of 220 = 2 × 2 × 5 × 11
Prime factorisation of 300 = 2 × 2 × 3 × 5 × 5 
Therefore, required L.C.M.
= 2 × 2 × 3 × 5 × 5 × 11 = 3,300 
Hence, 3,300 m far is the next heap that lies at the foot of a pole.

Long Answer Type Questions

Question 1. 
In a morning walk three persons step off together. Their steps measure 80 cm, 85 cm and 90 cm respectively. What is the minimum distance each should walk so that he can cover the distance in complete steps?
Answer:
We have to find the L.C.M. of 80 cm, 85 cm and 90 cm.
Prime factorisation of 80 = 2 × 2 × 2 × 2 × 5 
Prime factorisation of 85 = 5 × 17 
Prime factorisation of 90 = 2 × 3 × 3 × 5 
Therefore, required L.C.M
= 2 × 2 × 2 × 2 × 3 × 3 × 5 × 17 = 12,240

Therefore, required minimum distance = L.C.M. of 80 cm, 85 cm and 90 cm = 12,240 cm
= 122 m 40.cm (Since 1 m = 100 cm)