How many five-digit numbers are there, if the two leftmost digits are even, the other digits are odd and the digit 4 cannot appear more than once in the number.
Options:
(A) 1875
(B) 2000
(C) 2375
(D) 2500
(E) 3875 Let's think first. Stream of consciousness:
Number of combo with 4 as first digit + Number of combos with 4 as second digit = 1*4*5*5*5 + 3*5*5*5 = 2375
So, the answer is (C).