數字和是9的四位數一共有幾個
- 2022-12-25
9000,8100,7110,6111,
7200,6210,5211,
6300,5310,4311,
5400,4410,
很多。
當千位數是9時有一個9000
當千位數是8時有3個8100,8010,8001
當千位數是7時有6個,7200,7020,7002,7110,7101,7011。
當千位數是6時有7個,6111,6210,6201,6021,6012,6120,6102。
當千位數是5時有12個5400,5040,5004,5310,5301,5130,5103,5031,5013,5220,5202,5022
當千位是4時有21個4500,4050,4005,4410,4401,4140,4104,4014,4041,4320,4302,4230,4203,4032,4023,4311,4131,4113,4221,4212,4122
當千位是3時,有27個3600,3060,3006,3510,3501,3150,3105,3051,3015,3420 3402 3240 3204 3042 3024 3411 3141 3114 3330 3303 3033 3321 3312 3213
3231 3132 3123
當千位是2時有3+6+6+3+6+6+3+6=39個,當千位是1時有3+6+6+3+6+6+6+3+3=42個
一共158個
下一篇:吉他六線譜怎麼看的?