Prime Numbers

Q.

________ is the only even prime number

1. 1

2. 2

3. 16

4. 8

Q.

Express $36$ as a sum of two odd primes.

Q. The prime numbers between 40 and 50 are

1. 41, 43, 45, 47, 49
2. 41, 43, 47
3. 41, 43, 47, 51, 53
4. 37, 41, 43

Q.

Find prime factorization of $840$.

Q.

The largest 2-digit prime number is ______.

1. 97

2. 95

3. 91

4. 93

Q. Sum of two prime numbers between 10 and 20 is 36. The two numbers are

1. 17 and 19
2. 5 and 31
3. 13 and 23

Q.

Name two primes with product $35$.

Q.

Express following number as the sum of three prime numbers - :

$26=.........+..........+..........$

Q.

Find the missing number in the following series: $2,3,?,7,11$.

Q.

What are the properties of HCF and LCM?

Q.

Express the even number $20$ as the sum of any two odd prime numbers.

Q.

How many prime numbers up to $100$ have $3$ at their ones place?

Q.

Is $133$ a prime number?

Q.

Express following number as the sum of three prime numbers - :

$14=..........+........+...........$

Q.

Name two primes with sum $60$.

Q.

Name two primes with product $91$.

Q.

Express $72$ as a sum of two odd primes.

Q. Choose the prime number from the given even numbers.

1. 2
2. 12
3. 4
4. 8

Q. Is 23 a prime or composite number?

1. Prime number
2. Composite number
3. Cannot be determined

Q.

Write down the twin-primes between $40and50$.

_______________________________________

Q. Choose the incorrect statements.

1. $1$ is a prime number
2. All the even numbers are not prime numbers
3. Numbers of prime numbers between $1$ and $20$ are $8$
4. None of the above.

Q.

Express $40$ as a sum of two odd primes.

Q.

Express following number as the sum of three prime numbers - :

$12=..............+..................+............$

Q.

5. (i) Write all prime numbers between $70and100$.

Q.

Express following number as the sum of three prime numbers - :

$24=..............+.............+..............$

Q.

Express the even number $180$ as the sum of any two odd prime numbers.

Q. The smallest prime number is .

1. 1
2. 2
3. 3

Q.

Question 1

Which of the following statements are true:
(a) If a number is divisible by 3, it must be divisible by 9.
(b) If a number is divisible by 9, it must be divisible by 3.
(c) If a number is divisible by 18, it must be divisible by both 3 and 6.
(d) If a number is divisible by 9 and 10 both, then it must be divisible by 90.
(e) If two numbers are co-primes, at least one of them must be prime.
(f) All numbers which are divisible by 4 must also be divisible by 8.
(g) All numbers which are divisible by 8 must also be divisible by 4.
(h) If a number exactly divides two numbers separately, it must exactly divide their sum.
(i) If a number exactly divides the sum of two numbers, it must exactly divide the two numbers separately.

Q.

Write smallest odd composite number.

Q.

It is Samaira's birthday, she has bought chocolates for all her 40 classmates, and each student has been given a position to sit which is labeled from 1 to 40. She has bought two kinds of chocolates, one Dairy Milk and the other Munch. She will give Dairy Milk to those who are at the seats labeled by a prime number. How many children will get Dairy Milk chocolates?

1. 13
2. 21
3. 12
4. 11