How many six-digit numbers are there such that all six digits are different and the first digit is not zero?	Choose the correct choice from the following options.
A) 472392 B) 648421 C) 720756 D) 729951 E) 810364
All six digits are different and first digit is not zero.   So first digit can be filled in 9 ways.   And, second digit can be filled in 9 ways.   And, third digit can be filled in 9 ways.   And, fourth digit can be filled in 9 ways.   And, fifth digit can be filled in 9 ways.   And, sixth digit can be filled in 8 ways.   Total ways = 9*9*9*9*9*8= 
<gadget id="calculator">9*9*9*9*9*8</gadget>
<output>472_392</output>
472392   Hence option (472392).
<result>A</result>
How many six-digit numbers are there such that all six digits are different and the first digit is not zero?