用一条绳子在边长是80厘米的正方形桌面绕5周，一共需要绳子多少厘米？
计算下面各题．===﹣= 1﹣=﹣==﹣==
看谁算得又对又快．======．
3与4的倒数之差是多少？
算一算．+=﹣=+=+=﹣=﹣=
+= 1﹣=+=+= 1﹣=+=﹣=﹣=
=
=
=
﹣
= 1﹣
=
﹣
=
=
﹣
=
=
=
=
=
=
=
=．
+
=
﹣
=
+
=
+
=
﹣
=
﹣
=
+
= 1﹣
=
+
=
+
=
=
+
=
﹣
=
﹣
=
粤公网安备 44130202000953号