A four-character password consists of one letter of the alphabet and three different digits between 0 and 9,inclusive.The letter must appear as the second or third character of the password.How many different passwords are possible?答案是37440?
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![A four-character password consists of one letter of the alphabet and three different digits between 0 and 9,inclusive.The letter must appear as the second or third character of the password.How many different passwords are possible?答案是37440?](/uploads/image/z/10144925-53-5.jpg?t=A+four-character+password+consists+of+one+letter+of+the+alphabet+and+three+different+digits+between+0+and+9%2Cinclusive.The+letter+must+appear+as+the+second+or+third+character+of+the+password.How+many+different+passwords+are+possible%3F%E7%AD%94%E6%A1%88%E6%98%AF37440%3F)
A four-character password consists of one letter of the alphabet and three different digits between 0 and 9,inclusive.The letter must appear as the second or third character of the password.How many different passwords are possible?答案是37440?
A four-character password consists of one letter of the alphabet and three different digits between 0 and 9,inclusive.The letter must appear as the second or third character of the password.How many different passwords are possible?
答案是37440?
A four-character password consists of one letter of the alphabet and three different digits between 0 and 9,inclusive.The letter must appear as the second or third character of the password.How many different passwords are possible?答案是37440?
对
A(下标10上标3)*26*2=37440
A代表:10个数字(0-9)被随便排在除了字母那位剩下的三位中
26代表:字母的可能性(一共26个字母)
2代表:两种可能性——字母可出现在第二位/第三位上