
94 • Java Programming
Explanation: A number is prime if it is completely divisible by 1 and itself, e.g., 1, 3, 5, 7, 11, 13, 17, 19, 23, etc.
To check whether a number is prime or not, start from a counter c 2 ( every number divides by 1 ) and continue
till c num/2 since no number is completely divisible by a number which is more than half of that number.
For example, 12 is not divisible by 7, 8, 9, 10, 11 which are greater than 6. So it should be checked whether
the number divisible by any number num/2 is true; simply print ‘ Number is not prime ’ and exit from the
program, using System.exit(0). If num%c 0 is never true ...