Which is not a prime number ?
A. 13
B. 19
C. 21
D. 17
Answer: Option C
Solution(By Examveda Team)
21 = 3 × 7 is not a prime number because 21 is a composite number.Related Questions on Number System
Three numbers are in ratio 1 : 2 : 3 and HCF is 12. The numbers are:
A. 12, 24, 36
B. 11, 22, 33
C. 12, 24, 32
D. 5, 10, 15
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