How many 4 digit odd numbers do not use any digit more than once  Choose the correct answer
A) 1720  B) 2160  C) 224  D) 2460  E) None of these
The Way i solved it is   A B C D ( thousand , hundreds, tens, units)   D can be 1 3 5 7 9 ( any of the 5 digits )   A can be anything except (D or 0) so 8 possibilities   C can be anything execpt A and B so 8 possibilities   B can be anything execpt ( A D C ) so 7 possibilities   total ways are   8 * 7 * 8 * 5= 
<gadget id="calculator">  8 * 7 * 8 * 5</gadget>
<output>2_240</output>
2240   Ans None of these
<result>E</result>
How many 4 digit odd numbers do not use any digit more than once