(1)In the integer 3589 the digits are all different and increase from left to right. How many integers between 4000 and 5000 have digits that are all different and that increased from left to right?
比较题目:
(2)In the integer 3589 the digits are all different and increase from left to right. How many integers between 30000 and 50000 have digits that are all different and that increased from left to right?
(3)If p, r, m are three different prime numbers greater than 2, and n=p*r* m, how many positive factors, including 1 and n, does n have?
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(4)If p, r, m, n, t and s are six different prime numbers greater than 2, and n=p*r*s*m*n*t, how many positive factors, including 1 and n, does n have?
(5)If someone throws a dice twice, on the first time he gets a points, and on the second he gets b points, what is the probability a/b>1?
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(6)If someone throws a dice twice, what is the probability that the point he gets on one throw is bigger than the other?
(7) Mr. Jones must choose 4 of the following 5 flavors of jellybean: apple, berry, coconut, kumquat, and lemon, How many different combinations of flavors can Mr. Jones choose?