How many positive integers have no repeated digits?
The number of seven digit integers, with the sum of digits equal to 10 and formed by using the digits 1,2 and 3 only is,
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How many 8 digit numbers are there, such that they are divisible by 9 and all of the digits are distinct?
How many ways can you arrange 5 identical Rooks on a 6 by 10 Chessboard in such a way that none of the rooks attack each other ?
Consider all the 7-digit numbers containing each of the digits 1, 2, 3, 4, 5, 6, 7 exactly once and that are not divisible by 5. They are arranged in a list in increasing order. Find the 2000th number in this list.