Page 193 - New Medley 4 Semester 1

Numbers Factors Primes (P)/Composites (C)

9 1, 3, 9 C

10 1, 2, 5, 10 C

11 1, 11 P

12 1, 2, 3, 4, 6, 12 C

13 1, 13 P

14 1, 2, 7, 14 C

15 1, 3, 5, 15 C

16 1, 2, 4, 8, 16 C

17 1, 17 P

18 1, 2, 3, 6, 9, 18 C

19 1, 19 P

20 1, 2, 4, 5, 10, 20 C

Facts Regarding Prime and Composite Numbers

Z Z The number 1 has only one factor, so it is neither prime nor composite.

Z Z 2 is only the even number which is a prime. Rest all the primes are odd

numbers. 2 is the smallest prime number.

Z Z The two primes which differ by 2 are called twin primes, for example,
3 and 5, 5 and 7, etc.

Z Z The two numbers that have 1 as the common factor are called co-
primes. They may be either prime and composite or both primes or

both composites.

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