How many five-digit numbers that do not contain the digits 4 or 7 are there? Answers.
A) 44648	B) 27844	C) 28642	D) 16864	E) 32458
We can have 7 digits ( 1,2,3,5,6,8,9) for the first place ( ten thousand's place).   and similarly 8 digits for thousand's, hundred's, tenth's and unit digit. ( 0,1,2,3,5,6,8,9)   So in total 7*8*8*8*8= 
<gadget id="calculator">7*8*8*8*8</gadget>
<output>28_672</output>
28672   Hence 28642
<result>C</result>
How many five-digit numbers that do not contain the digits 4 or 7 are there?