503+497=
25+25×4=
52+25-52+25=
0.6÷100=
1.36×1000=
28÷4×7=
429-53-47=
15×4÷15×4=
42-42÷42
25×9×4=
1÷0.25= +1 = ×24= + =
400×0.02= 10÷ = 6 ×0= 3× ﹣ ×3=
2小时15分=小时 0.45立方米=立方分米