Twin prime numbers are two consecutive prime numbers that differ by 2. For example , of twin prime numbers : ( 3,5), (5 ,7), (11,13), (17,19) ,(29,31), (41,43) ,(59,61) ,(71,73 ) (101,103) ,(107,109) ,(137,139) ,(149,151) ,(169,181),(191,193),(197,199) ( 227,229),(239,241),(269,271) (281,283 ) (311,313) ,(347,349) ( 419,421) ,(431,433), (461,463)...................