how many four digits odd no. can be formed such that every 3 in the no, is followed by a 6?

Hi Gaurav,

There can be a maximum of one 3 in the four digit number.

The three cases

1)3 6 _ _

2)_ 36_ 

3)_ _ _ _ 

In the first case 36(9*4) numbers are possible

In the second case 32(8*2) numbers as possible

In the third case 2592(8*9*9*4) numbers possible

In total the number of cases = 2592+68 = 2660

Thanks,

Varun.