请列出用2、5、8、0这四个数字组成的所有四位数(数字可以重复使用)答:共有:3×4×4×4=192种 2000,2002,2005,2008,2020,2022,2025,2028,2050,2052,2055,2058,2080,2082,2085,2088,2200,2202,2205,2208,2220,2222,2225,2228,2250,2252,2255,2258,2280,2282,2285,2288,2500,2502,2505,2508,2520,2522,2525,2528,2550,2552,2555,2558,2580,2582,2585,2588,2800,...
2021的数字和是2+0+2+1二5,所有的三位数中,数字之和等于11的有多少个...答:当百位数字为5时,满足条件的数字有506,515,524,533,542,551,560共7个数字;当百位数字为6时,满足条件的数字有605,614,623,632,641,650共6个数字;当百位数字为7时,满足条件的数字有704,713,722,731,740共5个数字;当百位数字为8时,满足条件的数字有803,812,821,830共4个数字;当百位...