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Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,两位数减一位数退位减法,人教版小学数学一年级下册第六单元,口算,26-4= 49-5= 87-3=,38-10= 57-20= 76-40=,口算,26-4= 49-5= 87-3=,38-10= 57-20= 76-40=,想一想：怎样计算两位数减一位数、整十数的？,相同数位相减,22,36,37,28,84,44,探索新知,图中有哪些数学信息？,根据这些信息你能提一,个数学问,题吗？,我们班借,8,个足球。,还剩多少个足球？,36,8,我们班借,8,个足球。,30,6,？,36,8,28,个位上够减几就先减几，没减够就拆开一捆继续,减。,先,算,36,6,30,再,算,30,2,28,算法一,36,8,20,16,8,28,个位上不够减，打开一捆小棒和个位上合起来一起减。,算法二,算法一,算法二,36,8,28,先,算,36,6,30,再,算,30,2,28,36,8,2,0,1,6,8,28,32,5,20,12,7,32,5,32,2,30,30,3,27,27,12,5,7,20,7,27,27,44,9,30,14,5,44,9,44,4,14,40,40,5,35,35,9,5,30,5,35,35,30,6,0,减,6,不够减，,把,30,分成,20,和,10,，,先算,10,6,4,，,20,10,4,24,再算,20,4,24,。,这道题计算,时，也,是个位不够减，也是退位减法。,计算小达人,同学们，这节课你有什么收获？,再见,
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