2km2=m2。
1.25×80%= = 1﹣0.375= 6÷0.2=
= 2.35+4.7= = 16×0.25=
= =
①
②6.875﹣
③372÷25÷0.4
④77×
n
0
1
2
3
4
5
6
……
2n