用1-10这10个数可以组成多少组由不同4个数字组成的组数?答:0123,0124,0125,0126,0127,0128,0129 0134,0135,0136,0137,0138,0139 0145,0146,0147,0148,0149 0156,0157,0158,0159 0167,0168,0169 0178,0179 0189 0234,0235,0236,0237,0238,0239 0245,0246,0247,0248,0249 0256,0257,0258,0259 0267,0268,0269 0278,0279 0289 0345,0346,0347,0348,0349 03...