Prime and Composite Numbers
Prime and Composite Numbers
A prime number has only two factors: 1 and itself. A composite number has more than two factors. The number 1 is neither prime nor composite. The prime numbers between 2 and 31 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, and 31 since each of these numbers has only two factors,1 and itself.
When the area of a rectangle is a prime number, there is only one set of possible dimensions for that rectangle. When the area of a rectangle is a composite number, there are two or more sets of possible dimensions for that rectangle. Each set of dimensions is a pair of factors.
To determine if a number is prime or composite, follow these steps:
Illustration 1: Is the number 2 prime or composite?
Solution: The factors of 2 are 1 , and 2. Hence, 2 is prime.
Illustration 2: Is the number 9 prime or composite?
Solution: The factors of 9 are 1 x 9, 3 x 3. Hence, 9 is composite.
Illustration 3: Find the composite numbers which are multiple of 5 and less than 30.
Solution: As multiples of 5 which are less than 30 are 5, 10, 15, 20, 25
Now, factors of 5 = 1,5
factors of 10 = 1, 2, 5, 10
factors of 15 = 1, 3, 5, 15
factors of 20 = 1, 2 , 4, 5 , 10, 20
factors of 25 = 1, 5, 25
As 10, 15,20, 25 has more than 2 factors, Hence all these numbers are composite.
But 5 has only two factors, so 5 is prime.
Hence, the composite numbers which are multiple of 5 and less than 30 are 10, 15, 20, 25
The smallest prime number is ________ | |||
| Right Option : A | |||
| View Explanation | |||
The greatest 2- digit prime number is ______ | |||
| Right Option : D | |||
| View Explanation | |||
The prime number which comes just after 43 is: | |||
| Right Option : C | |||
| View Explanation | |||
Students / Parents Reviews [10]
Abhyas is a complete education Institute. Here extreme care is taken by teacher with the help of regular exam. Extra classes also conducted by the institute, if the student is weak.
Om Umang
10thOne of the best institutes to develope a child interest in studies.Provides SST and English knowledge also unlike other institutes. Teachers are co operative and friendly online tests andPPT develope practical knowledge also.
Aman Kumar Shrivastava
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Manish Kumar
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Cheshta
10thAbout Abhyas metholodology the teachers are very nice and hardworking toward students.The Centre Head Mrs Anu Sethi is also a brilliant teacher.Abhyas has taught me how to overcome problems and has always taken my doubts and suppoeted me.
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Prisha Gupta
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Shivam Rana
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