how many 5 - digit numbers that do not contain the digits 4 or 7 are there ?
Options
A) 44648 B) 27844 C) 28642 D) 16864 E) 32458

Rationale: 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 = 28672 hence c
Answer: C