估算297×51≈ 183÷29≈ 39×97≈ 630÷31≈
9999×9999+19999
÷[×(-)]
4.9×5+4.9+4.9×3
直接写出得数。6-+= 1-0.675= 1÷20%+0.36+0.4=÷= (+)×12= 1.25×0.9×80=+-+= 2.6×7.5+74×75%=×7÷×7= 199+200+201+202+203+204+205=
5x-12.5=2 3×(2x+7)=45 5.6-4x=3.2