×
30
6
20
600
120
3
90
18
+++=
10
5
40
400
200
2
﹣1 0.00010 × 0.75×800.75×800
0.3 1﹣ ﹣﹣ 1.5÷0.61.5×
1×1÷ 12亿203000000 428