how many 5 - digit numbers that do not contain the digits 4 or 7 are there ?
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
multiply(power(multiply(const_4, const_2), subtract(5, const_1)), 7)