①5.02元5元2角
②12.4+613
③500平方厘米5 平方分米
④2.7+3.47.9-0.8
6×12= 25×3= 60×70= 10×73=
42÷3= 9×800= 13×40= 10-10÷2=
50×40= 560÷8= 80×25= 80+90=
1.5÷0.05= 8÷0.001= 2.2+8= 31.9-3.09= 3×4÷3×4=
× = 5- + = × = 0.12= 1÷ - ÷1=