简便计算:90.1-9.9 （1\6+¼-1\8）×480 90.1×9.9 21+22+23+24+.+100

90.1-9.9= 90.1 - (10 - 0.1)= 90.1 - 10 + 0.1= 80.2（1\6+¼-1\8）×480 = (1/3 + 1/2 - 1/4)×240 = (1/3 + 1/4)×240 = (1/3 + 1/4)×12×20 = (4 + 3)×20 = 14090.1×9.9= 90.1×(10-0.1)= 901 - 9.01= 90...