有21个有23.434.23.243.4232.434.24.234.3243.242.32.432.342.223.334.4444.4344.2332.4423.3344.22
仅含1个数字,即2.22,3.33,4.44共3个, 仅含2,3, 则为 2.23, 2.32, 2.33, 3.23,3.32,3.22, 故共计4*3=12, 3个数字都包含,为6个数, 故总共21个小数
有21个有23.434.23.243.4232.4