Prime number:
The number which has no factors other than 1 and the number itself, is called a
prime number. Example: 2,3, 5 etc.
Prime numbers from 1 to 100 are below:
Prime numbers from 1 to 10 are 2, 3, 5, 7
Prime numbers from 11 to 20 are 11,
13, 17, 19
Prime numbers from 21 to 30 are 23,
29
Prime numbers from 31 to 40 are 31,
37
Prime numbers from 41 to 50 are 41,
43, 47
Prime numbers from 51 to 60 are 53,
59
Prime numbers from 61 to 70 are 61,
67
Prime numbers from 71 to 80 are 71,
73, 79
Prime numbers from 81 to 90 are 83, 89
Prime numbers from 91 to 100 are 97
The number of prime numbers from 1 to 100 is 25.
Composite number:
The number which has factors other than 1 and the number itself, is called a
composite number. Example: 4, 6, 9, etc.
Co - Prime
number: If the common factor of two or more
numbers are only 1, then the numbers are co-prime to each other.
Short question:
1. How many factors does a prime number has?
2. How many prime numbers between 1 and 100?
3. 50 has --------------- prime factors.
4. Which one of the following pairs of numbers are coprime numbers?
(i) 16,35 (ii) 21,143 (iii) 112,125 (iv) 144,189
5. What is the difference between the greatest and least
prime numbers from 1 and 100?
6. Average is ---------------- of prime numbers from 1
and 20.
7. Summation of prime number from 20 to 60 is --------------------
8. How many prime numbers between 30 & 70? (a) 8 (b)
7 (c) 9 (d)
10
9. How many prime numbers are there from 15 to 50?
10. What is the difference between prime numbers which
is less than 90 but greater than 10?
11. Which one of the following pairs of numbers are coprime numbers?
(i) 12,18 (ii)
19,38 (iii)22, 27 (iv) 28, 35
12. Which one of the following pairs of
numbers are not coprime numbers?
(i)16,35 (ii)21,143 (iii)112,125 (iv)144,189
13. What are the prime factors of 21?
14. What are the prime factors of 280?
15. If two numbers have no prime factors then these are
------------------
16. What is the least prime number of two digits?
17. What is the least prime number of three digits?
18. Sum of two prime numbers is equal to the product of 3
and 4. What are they?
19. Only --------------- is prime number in even
number.
20. Summation of prime number from 1 to 100 is
--------------------
21. Average of prime number from 1 to 100 is
------------------------
22. If five times of sum of two prime numbers of one
digit is 60 then what are the prime numbers?
23. If two numbers are coprime number to each other
then their H. C. F ----------
24. If two or more numbers are divided by their H. C.
F then their quotient is called -----
25. How many prime numbers from 60 to
80?
26. What is the least prime number?
27. What is the greatest prime number?
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