①2.4×0.7÷2.4×0.7
②7.8×99
③13.56-3.56÷8
④12.4÷1.25÷0.8
9×3.14= +÷= 36×= 728﹣299=
72÷0.4= 75×10%= 1÷×= 12.56÷6.28=