permutation and combination

Asked by  | 17th Mar, 2009, 11:55: PM

Expert Answer:

For  a four digit number to be even it can have only 0,2,4,6 or 8 in its unit's place.

So,

 the unit's place can be filled up  in 5 ways.

The thousand's place can't have zero in it , for the number to be a four digit number.So, the thousand's place can be filled in 9 ways (by one of the digits1,2,3...,9)

The remaining 2 places can be filled by any one of the ten digits from 0 to 9.

So,

 the total number of ways

=9*10*10*5=4500

Answered by  | 18th Mar, 2009, 11:17: PM

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