①
②
(+)×9= 1.5×100= 99×0.8+0.8= 42=
+= 7﹣= ×= ÷=
420﹣298= 4+5.6= = =
0.25×0.4= 0.133= = =
56+44= 0.9×0.6= 20﹣3.7= 8÷100= 2.5×3.5×4=
-= += 10÷= 15×= ×24+24=