Questions :
Identify the odd one: 3, 5, 7, 11, 13, 17, 19, 21
Options :
- (a) 21
- (b) 13
- (c) 11
- (d) 19
correct answer : a)
Explanation :
All numbers in the sequence are prime numbers except 21, which is a composite number ($3 times 7 = 21$). Hence, the correct answer is option (a) 21.