（1）量出右图线段的长是 厘米．（取整厘米数） （2）在线段AB上取一点O，使AO=AB．（3）以O为圆心，以OB为半径画一个圆．（4）计算这个圆的面积．
直接写得数 4÷= 0×=÷=×1.4=×= 0÷=×10= 30×0.05=
直接写出得数．========
口算． 4.2÷=×3=÷5=（+）×72=×12=×1.8=÷=
========
直接写出得出． 20×=÷=×=+=÷6=×12=+= 6÷=﹣=×=×= 0÷=
AB．
= 0×
=
÷
×1.4=
×
=
×10= 30×0.05=
=
=
=
=
=
=
=
=
=
×3=
÷5=（
+
）×72=
×12=
÷
=
=
=
=
=
=
=
=
=
÷
=
×
=
+
=
÷6=
+
= 6÷
=
﹣
=
×
=
×
= 0÷
=
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