6th Maths : Term 2 Unit 1 : Numbers : Exercise 1.1 : Text Book Back Exercises Questions with Answers, Solution

__Exercise
1.1__

** **

__1. Fill in the blanks__

**(i)
The number of prime numbers between 11 and 60 is **__12__**.**

**(ii)
The numbers 29 and **__31__** are twin primes.**

**(iii)
3753 is divisible by 9 and hence divisible by **__3__**.**

**(iv)
The number of distinct prime factors of the smallest 4 digit number is **__2__**.**

**(v)
The sum of distinct prime factors of 30 is **__10____ (2 + 3 + 5 = 10)__**.**

** **

**2. Say True or False**

**(i)
The sum of any number of odd numbers is always even.**

**(ii)
Every natural number is either prime or composite.**

**(iii)
If a number is divisible by 6, then it must be divisible by 3.**

**(iv)
16254 is divisible by each of 2, 3, 6 and 9.**

**(v)
The number of distinct prime factors of 105 is 3.**

** **

**3.
Write the smallest and the biggest two digit prime number.**

The smallest prime number = 11

The bigger prime number = 97

** **

**4.
Write the smallest and the biggest three digit composite number.**

The smallest composite number = 100

The biggest composite number = 999

** **

**5.
The sum of any three odd natural numbers is odd. Justify this statement with an
example.**

Yes. 5 + 7 + 9 = 21

** **

**6.
The digits of the prime number 13 can be reversed to get another prime number 31.
Find if any such pairs exist upto 100.**

(17,71), (37,73), (79,97)

** **

**7.
Your friend says that every odd number is prime. Give an example to prove him/her
wrong.**

False. 15 is odd number but
not prime number.

** **

**8.
Each of the composite numbers has atleast three factors. Justify this statement
with an example.**

True. The composite number
4 has three factors 1, 2 and 4.

** **

**9.
Find the dates of any month in a calendar which are divisible by both 2 and 3.**

The dates in a calendar
which are divisible by both 2 and 3 are 6, 12, 18, 24, 30 (Excluding February).

** **

**10.
I am a two digit prime number and the sum of my digits is 10. I am also one of the
factors of 57. Who am I?**

Factors of 57 are 1, 3, 19 and 57

Two digit prime number 19

sum of the digits 1 + 9 = 10

** **

**11.
Find the prime factorisation of each number by factor tree method and division method.**

**a)
60 b) 128 c) 144 d) 198 e) 420 f) 999**

**a) 60**

**b) 128**

**c) 144**

**d) 198**

**e) 420**

**Factor tree method : ****420 = 2 × 2 × 3 × 5 × 7**

**Division method : ****420 = 2 × 2 × 3 × 5 × 7**

**f) 999**

**Factor tree method : ****999 = 3 × 3 × 3 × 37**

**Division method : ****999 = 3 × 3 × 3 × 37**

** **

**12.
If there are 143 math books to be arranged in equal numbers in all the stacks, then
find the number of books in each stack and also the number of stacks.**

If the number of stacks 11, number of books in each stacks are
13

If the number of stacks 13, number of books in each stacks are
11.

** **

__Objective Type Questions__

**13.
The difference between two successive odd numbers is**

**a)
1 **

**b)
2 **

**c)
3 **

**d)
0**

**Answer: b) 2**

** **

**14.
The only even prime number is **

**a)
4 **

**b)
6 **

**c)
2 **

**d)
0**

**Answer: c) 2**

** **

**15.
Which of the following numbers is not a prime?**

**a)
53 **

**b)
92 **

**c)
97**

**d)
71**

**Answer: b) 92**

** **

**16.
The sum of the factors of 27 is **

**a)
28 **

**b)
37**

**c)
40 **

**d)
31**

**Answer: c) 40**

** **

**17.
The factors of a number are 1, 2, 4, 5, 8, 10, 16, 20, 40 and 80.What is the number?**

**a)
80**

**b)
100 **

**c)
128 **

**d)
160**

**Answer: a) 80**

** **

**18.
The prime factorisation of 60 is 2 ×2 × 3 × 5. Any other number which has the same
prime factorisation as 60 is**

**a)
30 **

**b)
120 **

**c)
90 **

**d)
impossible**

**Answer: d) impossible**

** **

**19.
If the number 6354 * 97 is divisible by 9, then the value * is**

**a)
2 **

**b)
4 **

**c)
6 **

**d)
7**

**Answer: a) 2**

** **

**20.
The number 87846 is divisible by **

**a)
2 only **

**b)
3 only **

**c)
11 only **

**d)
all of these**

**Answer: d) all of these**

** **

__ANSWERS: __

__Exercise 1.1 __

**1. i) 12 ii) 31
iii) 3 iv) 2 v) 10**

**2. i) False ii)
False iii) True iv) True v) True **

**3. smallest → 11;
biggest → 97 **

**4. smallest → 100;
biggest → 999**

**5. True. 3 + 7 + 9
= 19 is odd**

**6. (17, 71),
(37,73) & (79,97)**

**7. False. 9 is odd
number but not prime**

**8. True. The
composite number 4 has 3 factors namely 1, 2, and 4.**

**9. 6, 12, 18, 24,
30 (excluding February)**

**10. 19**

**11. a) 60 = 2 × 2 ×
3 × 5**

** b) 128 = 2 × 2 × 2 × 2 × 2 × 2 × 2**

** c) 144 = 2 × 2 × 2 × 2 × 3 × 3**

** d) 198 = 2 × 3 × 3 × 11**

** e) 420 = 2 × 2 × 3 × 5 × 7**

** f) 999 = 3 × 3 × 3 × 37**

**12. (11, 13) or
(13, 11)**

**Objective Type
Questions **

**13. b) 2 **

**14. c) 2 **

**15. b) 92 **

**16. c) 40**

**17. a) 80 **

**18. d) impossible **

**19. a) 2**

**20. d) all of these**

Tags : Questions with Answers, Solution | Numbers | Term 2 Chapter 1 | 6th Maths , 6th Maths : Term 2 Unit 1 : Numbers

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6th Maths : Term 2 Unit 1 : Numbers : Exercise 1.1 | Questions with Answers, Solution | Numbers | Term 2 Chapter 1 | 6th Maths

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