用0，1，2，3，4这五个数字组成无重复数字的自然数．（1）在组成的三位数中，求所有偶数的个数；（2）在组成的三位数中，如果十位上的数字比百位上的数字和个位上的数字都小，则称这个数为“凹数”，如301,423等都是“凹数”，试求“凹数”的个数；（3）在组成的五位数中，求恰有一个偶数数字夹在两个奇数数字之间的自然数的个数．略河北省邢台一中学年高二下学期第一次月考数学理试题答案The page is temporarily unavailable
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