3,4四个数字可以组成数字不重复和自然数的个数是多少?
一位数:1,2,3,4,
(4个)
二位数:|12,13,14,
(12个)|21,23,24,
|31,32,34,
|41,42,43,
三位数:|123,124,132,142,
(16个)|213,214,231,234
|312,314,321,324
|412,413,421,423
四位数:|1234,1243,1324,1342,1423,1432
(24个)|2134,2143,2341,2314,2413,2431
|3124,3142,3214,3241,3412,3421
|4321,4312,4123,4132,4213,4231
以上是不重复的数,一共56个
再...全部
一位数:1,2,3,4,
(4个)
二位数:|12,13,14,
(12个)|21,23,24,
|31,32,34,
|41,42,43,
三位数:|123,124,132,142,
(16个)|213,214,231,234
|312,314,321,324
|412,413,421,423
四位数:|1234,1243,1324,1342,1423,1432
(24个)|2134,2143,2341,2314,2413,2431
|3124,3142,3214,3241,3412,3421
|4321,4312,4123,4132,4213,4231
以上是不重复的数,一共56个
再加上可重复的自然数:
二位数:11,22,33,44(4个)
三位数:|111,121,122,131,133,141,144,
(28个) |222,211,212,232,223,242,224,
|333,313,331,323,332,343,334,
|444,414,441,424,442,434,443,
四位数:|1111,1112,1113,1114,
( |1121,1122,1123,1124,
|1131,1132,1133,1134,
|1141,1142,1143,1144,
|1211,1212,1213,1214,
|1221,1222,1223,1224,
|1231,1232,1233,1234,
|1241,1242,1243,1244,
|1311,1312,1313,1314,
|1321,1322,1323,1324,
|1331,1332,1333,1334,
|1341,1342,1343,1344,
|1411,1412,1413,1414,
|1421,1422,1423,1424,
|1431,1432,1433,1434,
|1441,1442,1443,1444,
|2111,2112,2113,2114,
|2121,2122,2123,2124,
|2131,2132,2133,2134,
|2141,2142,2143,2144,
|2211,2212,2213,2214,
|2221,2222,2223,2224,
|2231,2232,2233,2234,
|2241,2242,2243,2244,
|2311,2312,2313,2314,
|2321,2322,2323,2324,
|2331,2332,2333,2334,
|2341,2342,2343,2344,
|2411,2412,2413,2414,
|2421,2422,2423,2424,
|2431,2432,2433,2434,
|2441,2442,2443,2444,
|3111,3112,3113,3114,
|3121,3122,3123,3124,
|3131,3132,3133,3134,
|3141,3142,3143,3144,
|3211,3212,3213,3214,
|3221,3222,3223,3224,
|3231,3232,3233,3234,
|3241,3242,3243,3244,
|3311,3312,3313,3314,
|3321,3322,3323,3324,
|3331,3332,3333,3334,
|3341,3342,3343,3344,
|3411,3412,3413,3414,
|3421,3422,3423,3424,
|3431,3432,3433,3434,
|3441,3442,3443,3444,
|4111,4112,4113,4114,
|4121,4122,4123,4124,
|4131,4132,4133,4134,
|4141,4142,4143,4144,
|4211,4212,4213,4214,
|4221,4222,4223,4224,
|4231,4232,4233,4234,
|4241,4242,4243,4244,
|4311,4312,4313,4314,
|4321,4322,4323,4324,
|4331,4332,4333,4334,
|4341,4342,4343,4344,
|4411,4412,4413,4414,
|4421,4422,4423,4424,
|4431,4432,4433,4434,
|4441,4442,4443,4444,。
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