Number of natural number upto one lakh, which contains 1,2,3, exactly once and remaining digits any time is--
100000
3 digit 1 2 3 =3 ! =6
4 digit 1 2 3 =6c1.4!
(without 0) =144
(with 0) 1 2 3 =3c1×3!
=1θ
5 digit................ 5c3.3!×36
(without 0) =2160
(with 10) ................. 4c1.4!×6 =576
(with 20) 1......2..3 4c2.3! =36
=2940