Prime Numbers: A number which has only two different factors, 1 and the number itself is called prime number. e.g. 2, 3, 5, 7
Co-Prime Numbers: Two numbers are said to be co-prime when they have only 1 as common factor.e.g. 3 and 5: 19 and 20
Twin Prime Numbers: Two prime numbers whose difference is 2 are called are called Twin Prime Numbers. e.g. 3 and 5: 41 and 43.
Illustration: State whether the following numbers are co-prime or not.
(i) 4 and 17
(ii) 25 and 15
(iii) 13 and 19
(iv) 56 and 12
Solution: (i) As 4 and 17 have only 1 as common factor. Hence 4 and 17 are co-prime numbers.
(ii) As 25 and 15 have common factors as 5,1 . Hence 25 and 15 are not co-prime numbers.
(iii) As 13 and 19 have only 1 as common factor. Hence 13 and 19 are co-prime numbers.
(iv) As 56 and 12 have common factors as 2, 4,1. Hence 56, 12 are not co-prime numbers.
Illustration: How many twin prime numbers are there in between 90 and 100?
Solution: There are no Twin Prime Numbers between 90 and 100.
Consider the following statement : i. The product of two composite numbers remains same on changing their order. ii. The product of a pair of co-primes is changed on changing their order. | |||
Right Option : C | |||
View Explanation |
Example for co-prime mumbers is: | |||
Right Option : A | |||
View Explanation |
23 and 24 are co-prime numbers or not? | |||
Right Option : A | |||
View Explanation |
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