There are 10 periods in each working day of a school. In how many ways can one organize 9 subjects such that each subject is allowed at least one period?  Choose the correct answer
A) 16329600
B) 16356789
C) 16324600
D) 15679892
E) None of these
9 subjects can be arranged in 10 periods in 10P9 ways.   Remaining 1 period can be arranged in 9P1 ways.   Two subjects are alike in each of the arrangement. So we need to divide by 2! to avoid overcounting.   Total number of arrangements = (10p9 x 9P1)/2! = 16329600   16329600NSWER:16329600
<result>A</result>
There are 10 periods in each working day of a school. In how many ways can one organize 9 subjects such that each subject is allowed at least one period?