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1、第三讲第三讲简单的推理简单的推理做个聪明的小朋友做个聪明的小朋友做个聪明的小朋友做个聪明的小朋友 多观察多观察多观察多观察 多动脑多动脑多动脑多动脑 多分析多分析多分析多分析例题例题1:一个菠萝和几个橘子一样重?4 4举一反三(举一反三(1)1、1 个 = 3 个1 个 = 3 个 1 个 =( )个 92、1头猪 - 2只羊1只羊 - 4只兔2只羊 -( )只兔1头猪 -( )只兔换换换换88例题例题2:?个?个 想一想!想一想!6 6举一反三(举一反三(2):):1、?个?个8 82、1支钢笔的价格支钢笔的价格=2支中性笔的价格支中性笔的价格1支中性笔的价格支中性笔的价格=4块橡皮的价格块
2、橡皮的价格3支钢笔的价格支钢笔的价格=( )块橡皮的价格)块橡皮的价格2424例题例题3:(1 1) - 4 = 6 = - 4 = 6 = ( ) + = 13 = + = 13 = ( )(2 2) 9 + = 10 9 + = 10 = = ( ) - = 10 = - = 10 = ( ) 10103 31 19 9举一反三(举一反三(3):):(1 1) + 5 = 12+ 5 = 12 = = ( ) + = 20 = + = 20 = ( )(2 2) 20 + = 6 = 20 + = 6 = ( ) - = 10 = - = 10 = ( )4 47 714141313例题例题4: + + + + = 14 + + + + + + = 18 = ( )= ( )2 24 4举一反三(举一反三(4) + + = 24 + + + + = 32 1、= ( )= ( )4 410102、 + + + = 40 + + + + + + = 55 = ( )= ( )5 51 15 5例题例题5: + = 6 = ( ) + = 8 = ( )3 35 5举一反三(举一反三(5):):1、 + = 6 = ( ) + = 8 = ( )3 35 52、 + = 10 = ( ) + + = 6 = ( ) + + = 8 = ( )2 23 37 7