每盒装12枝圆珠笔，每枝圆珠笔2元钱，①每盒圆珠笔多少钱？②5盒共有多少枝圆珠笔？
（+）++++﹣+．
用你认为简便的方法计算． ．
+= ﹣= += +=1﹣= += ﹣+= ++=
0.5+ ．
直接写出计算结果．+= += += = 1﹣= =
+
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+
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+
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．
+
= 
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= 
+
= 
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﹣
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= 1﹣
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