直接写出得数．
2﹣1.7= 9.9÷
0.5+1
×3.5
0.9×99+0.9（
+
）×30 3÷2.8（估算）≈ 0.312×2（得数保留1位小数）≈
口算
56+37= 80﹣16= 31.5+5= 12﹣1.1=
2×0.2= 2.87÷0.7= 30÷50= 25×8=
= 12×
=
×
=
=
1÷
= 0×
=
+
=
=
下面各题怎样算就怎样算．
（
+
）÷
+
+…+
÷
+
÷
2011÷
．
直接写得数
0.8×0.6= 2﹣
= 1÷
=
×
=
7.2÷8×4= 3.25×4= 3.3﹣0.7= 0.9+99×0.9=
9÷
=
+
=
+﹣+=（0.18+0.9）÷9=
口算
1.87+5.3=（
+
）×56= 10×
÷×10=÷
=