Page 160 - Ganit Kaushal

Chapter Test

I. Multiple Choice Questions (MCQs)

1. Every composite number has at least
(a) 1 factor (b) 2 factors (c) 3 factors (d) 4 factors

2. The number of natural numbers between the smallest natural number and the greatest two-digit number
is
(a) 90 (b) 97 (c) 98 (d) 99

3. Which of the following is a prime factor of the largest three-digit number?
(a) 111 (b) 9 (c) 27 (d) 37
4. Prime factorisation of 12 is

(a) 12 (b) 12 (c) 12 (d) 12

3 2 3 4 12 1 6 2

3 1 2 1 2 2 3 3
5. For a number to be divisible by 72, it is sufficient to check divisibility of the number by

(a) 6 only (b) 12 and 18 both (c) 14 and 8 both (d) 8 and 9 both
6. 88 is expressed as the sum of two odd primes. Which of the following is incorrect?

(a) 83 + 5 (b) 79 + 9 (c) 71 + 17 (d) 59 + 29
7. The number of prime numbers lying between 1 and 100 is
(a) 23 (b) 24 (c) 25 (d) 26

II. Fill in the blanks.

1. Every number is a __________ of itself.
2. __________ and __________ are always factors of a given number.
3. The smallest even prime number is __________.

4. Co-prime numbers have only __________ as their common factor.
5. Prime numbers whose difference is two are called __________ numbers.

6. The smallest odd composite number is __________.
7. __________ is a divisor of every number.
8. __________ is divisible by every number.

9. In the division algorithm a = bq + r, if r = 0, then b and q are called __________ of ‘a’.
III. State whether the following statements are true or false.

1. All odd numbers are prime numbers.
2. A square number is always a composite number.

3. A perfect number is a number which is the sum of all its factors.

158