Prime and Composite Numbers


 
 
Concept Explanation
 

Prime and Composite Numbers

Prime and Composite Numbers:

We are now familiar with the factors of a number. Observe the number of factors of a few numbers arranged in this table.

NumbersFactorsNumber of Factors

1

2

3

4

5

6

7

8

9

10

11

12

1

1,2

1,3

1,2,4

1,5

1,2,3,6

1,7

1,2,4,8

1,3,9

1,2,5,10

1,11

1,2,3,4,6,12

1

2

2

3

2

4

2

4

3

4

2

6

 

We find that (a) The number 1 has only one factor (i.e. itself)

(b) There are numbers, having exactly two factors 1 and the number itself. Such number are 2,3,5,7,11 etc. These numbers are prime numbers.

      The numbers other than 1 whose only factors are 1 and the number itself are called prime numbers.

(c) There are numbers having more than two factors like 4, 6, 8, 9, 10 and so on.

       These numbers are composite numbers.

      Numbers having more than two factors are called composite numbers.

1 is neither a prime nor a composite number

 

 

 

 

 

Sample Questions
(More Questions for each concept available in Login)
Question : 1

The smallest composite number is __________.

Right Option : C
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Explanation
Question : 2

__________________ are 5 consecutive composite numbers less than 100 so that there is no prime number between them .

Right Option : C
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Explanation
Question : 3

If p is the prime number that (p+2) is also a prime number , then p(p+2)+1 is always ___________________

 

Right Option : D
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Explanation
 
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