用塑料绳捆扎一个圆柱形的蛋糕盒（如下图），打结处正好是底面圆心，打结用去绳长10厘米。（1）扎这个盒子至少用去塑料绳多少厘米？（2）在它的整个侧面贴上商标和说明，这部分的面积至少是多少平方厘米？
直接写出得数．×=××=÷3= 12×=+﹣+= 20÷= 18÷÷=×= 0×=×÷×=
口算 56×= 2﹣=+= 6×= 0.25×4= 57×=÷= 1÷= 21÷=÷= 1÷= 0÷=
计算下面各题．×21×÷5×÷÷÷÷24×÷8．
计算．×9=×0= 0÷=÷= 12×=×=÷=÷=
直接写得数×=÷5=×12=×=÷=÷=×= 1÷== 45×=÷2=÷=×=÷=×0=×= 1﹣=÷=×= 15÷=
×
=
×
×
=
÷3= 12×
=
+
﹣
+
=
= 18÷
÷
=
= 0×
=
×
÷
= 2﹣
=
+
= 6×
= 0.25×4= 57×
=
÷
= 1÷
= 21÷
=
÷
= 1÷
= 0÷
=
×21×
÷5×
÷
÷
÷
÷24
×
÷8．
×9=
×0= 0÷
=
÷
=
×
=
÷
=
÷
=
×
=
÷5=
×12=
×
=
÷
÷
=
×
= 1÷
=
= 45×
=
÷2=
÷
=
×
=
=
×0=
×
= 1﹣
=
÷
=
×
= 15÷
=
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