Counting numbers have fascinated human mind from time immemorial. The first set he seems to have pondered about is the set of natural numbers, N Various subsets of this set were diffined. Note worthy among them are
Prime Number :- if a natural number has exactly tow divisors it is called a prime number. Yet another way Simple examples are `2,3,5,7,...........`
`{2,3}` in the only set of consective primes.
Composite numbers :- A natural number habing more than 2 divisors is called a composite number. Simple examples are `4,6,8,9,10,..........`
Note that 1 is neither prime nor composite.
Coprime or relatively prime numbers :- A pair of natural numbers is acalled a set of coprime numbers if their highest common factor (HCF) or greatest common divisor (g.c.d.) is 1. For example 8 & 5 are co-prime
Note that these two numbers need not be prime.
More over 1 is coprime with evert natural numbers.
a prime number is coprime with all natural numbers which are not it's multiple.
Twin Prime :- A pair of primes is called twin primes if their non-negative difference is '2' For example `{3,5} , {5,7}, (11,13} , .........
Based on above difinitions solve that following problems
Number of prime numbers less than 10 is

Counting numbers have fascinated human mind from time immemorial. The first set he seems to have pondered about is the set of natural numbers, N Various subsets of this set were diffined. Note worthy among them are Prime Number :- if a natural number has exactly tow divisors it is called a prime number. Yet another way Simple examples are 2,3,5,7,........... {2,3} in the only set of consective primes. Composite numbers :- A natural number habing more than 2 divisors is called a composite number. Simple examples are 4,6,8,9,10,.......... Note that 1 is neither prime nor composite. Coprime or relatively prime numbers :- A pair of natural numbers is acalled a set of coprime numbers if their highest common factor (HCF) or greatest common divisor (g.c.d.) is 1. For example 8 & 5 are co-prime Note that these two numbers need not be prime. More over 1 is coprime with evert natural numbers. a prime number is coprime with all natural numbers which are not it's multiple. Twin Prime :- A pair of primes is called twin primes if their non-negative difference is '2' For example {3,5} , {5,7}, (11,13} , ......... Based on above difinitions solve that following problems Number of composite numbers less than 15 is

Counting numbers have fascinated human mind from time immemorial. The first set he seems to have pondered about is the set of natural numbers, N Various subsets of this set were diffined. Note worthy among them are Prime Number :- if a natural number has exactly two divisors it is called a prime number. Yet another way Simple examples are 2,3,5,7,........... {2,3} in the only set of consective primes. Composite numbers :- A natural number having more than 2 divisors is called a composite number. Simple examples are 4,6,8,9,10,.......... Note that 1 is neither prime nor composite. Coprime or relatively prime numbers :- A pair of natural numbers is acalled a set of coprime numbers if their highest common factor (HCF) or greatest common divisor (g.c.d.) is 1. For example 8 & 5 are co-prime Note that these two numbers need not be prime. More over 1 is coprime with evert natural numbers. a prime number is coprime with all natural numbers which are not it's multiple. Twin Prime :- A pair of primes is called twin primes if their non-negative difference is '2' For example {3,5} , {5,7}, (11,13} , ......... Based on above difinitions solve that following problems Number of composite numbers less than 15 is "(a) 10 (b) 9 (c) 8 (d) 7"

Counting numbers have fascinated human mind from time immemorial. The first set he seems to have pondered about is the set of natural numbers, N Various subsets of this set were diffined. Note worthy among them are Prime Number :- if a natural number has exactly tow divisors it is called a prime number. Yet another way Simple examples are 2,3,5,7,........... {2,3} in the only set of consective primes. Composite numbers :- A natural number habing more than 2 divisors is called a composite number. Simple examples are 4,6,8,9,10,.......... Note that 1 is neither prime nor composite. Coprime or relatively prime numbers :- A pair of natural numbers is acalled a set of coprime numbers if their highest common factor (HCF) or greatest common divisor (g.c.d.) is 1. For example 8 & 5 are co-prime Note that these two numbers need not be prime. More over 1 is coprime with evert natural numbers. a prime number is coprime with all natural numbers which are not it's multiple. Twin Prime :- A pair of primes is called twin primes if their non-negative difference is '2' For example {3,5} , {5,7}, (11,13} , ......... Based on above difinitions solve that following problems Let p & q be the number of natural numbers which are less than or equal 20 and are prime & composite respectively, then 20-p-q is equal to "(a) 1 (b) 0 (c) 2 (d) 3"

Counting numbers have fascinated human mind from time immemorial. The first set he seems to have pondered about is the set of natural numbers, N Various subsets of this set were diffined. Note worthy among them are Prime Number :- if a natural number has exactly tow divisors it is called a prime number. Yet another way Simple examples are 2,3,5,7,........... {2,3} in the only set of consective primes. Composite numbers :- A natural number habing more than 2 divisors is called a composite number. Simple examples are 4,6,8,9,10,.......... Note that 1 is neither prime nor composite. Coprime or relatively prime numbers :- A pair of natural numbers is acalled a set of coprime numbers if their highest common factor (HCF) or greatest common divisor (g.c.d.) is 1. For example 8 & 5 are co-prime Note that these two numbers need not be prime. More over 1 is coprime with evert natural numbers. a prime number is coprime with all natural numbers which are not it's multiple. Twin Prime :- A pair of primes is called twin primes if their non-negative difference is '2' For example {3,5} , {5,7}, (11,13} , ......... Based on above difinitions solve that following problems Let p & q be the number of natural numbers which are less than or equal 20 and are prime & composite respectively, then 20-p-q is equal to

Is the set of natural numbers a finite set?

Set of even prime number is a

If A is a set of first 10 natural numbers then number of subsets of A are

If A is a set of first 10 natural numbers then number of subsets of A are

2 is……………of set of natural numbers.