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1、小數(shù)的意義和讀寫,0.3元,0.05元,0.48元,橡皮的單價 0.3元是3角,信封的單 價是5分。,練習本的單價是4角8分,也可以說成是48分。,橡皮,信封,練習本,用”角”或”分”作單位,說說價格,1元=10角 1角= 元,復習:一位小數(shù),1元=100分 1分= 元,0.05元 = 5 分= 元 0.48元=4角8分=48分= 元,1分= 0.01元= 元,0.01讀作:零點零一, 0.05讀作:零點零五, 0.48讀作:零點四八。 請讀一讀,再舉幾個這樣的例子,同桌之間相互說一說。,把1米平均分成100份,每份長1厘米。1厘米是 。,0.01米,米,,例2,米,把
2、4厘米和9厘米寫成分數(shù)和小數(shù)各是多少?,0.01米,米,,,,0.04,0.09,例2,0.001米,,把1米平均分成1000份,每份是1毫米。1毫米是 。,把7毫米和15毫米寫成分數(shù)和小數(shù)各是多少?,0.007米,,,0.015米,0.04米,0.015米,0.3元,比較上面每組中的分數(shù)和小數(shù),你能發(fā)現(xiàn)什么?想一想,還有沒有位數(shù)更多的小數(shù)?在小組里進行交流。,米,,元,,分母是10、100、1000的分數(shù)都可以用小數(shù)表示。 一位小數(shù)表示十分之幾,兩位小數(shù)表示百分之幾,三位小數(shù)表示千分之幾,一個小數(shù)的小數(shù)部分含有幾個數(shù)位,這個小數(shù)就是幾位小數(shù)。 如0.3是一位小數(shù),0.04是兩位小數(shù),0.007是三位小數(shù)。 顯然,還有小數(shù)位數(shù)更多的小數(shù)。,0.7,0.43,0.009,讀出下面各數(shù),并說出各表示幾分之幾。,0.39,0.108,0.006,0.5,0.80,,,,,,( ),( ),( ),( ),( ),( ),在括號里填上合適的小數(shù)。,0.3,0.256,0.021,0.8,0.37,0.02,