text: This is checked so that we can skip the middle five numbers in the below loop
code: if ( n % 2 == 0 or n % 3 == 0 ) return true ; int i = 5 ; while ( i * i <= n ) { if ( n % i == 0 or n % ( i + 2 ) == 0 ) return true ; i = i + 6 ; } return false ; }