2023年五年級(jí)數(shù)學(xué)上冊(cè)1小數(shù)乘法第4課時(shí)小數(shù)乘小數(shù)2上課課件新人教版

,小數(shù)乘小數(shù)（,2,）,R,五年級(jí)上冊(cè),一、復(fù)習(xí)鋪墊,0.9,5,4.5,1.,計(jì)算下面各題。,=4.5,0.95,15.41.2,1 5.4,1.2,3 0 8,1 5 4,1 8.4 8,=18.48,小數(shù)乘整數(shù)以及小數(shù)乘小數(shù)是怎樣計(jì)算的？,0.56,0.04=_,兩位小數(shù),兩位小數(shù),(),位小數(shù),0.5 6,0.0 4,2 2 4,0.0224,要在前面用,0,補(bǔ)足位數(shù)，再點(diǎn)小數(shù)點(diǎn)。,0.5 6,0.0 4,2 2 4,0,.,0,四,二、探究新知,乘得的積的小數(shù)位數(shù)不夠，怎樣點(diǎn)小數(shù)點(diǎn)？,積的位數(shù)夠,積的位數(shù)不夠，要添零,先添零，再去末尾的零,觀察這幾個(gè)例子，說(shuō)說(shuō)小數(shù)乘法該注意些什么？,1,.,積的位數(shù)不夠時(shí)，要添,0,占位，再點(diǎn)小數(shù)點(diǎn)。,2,.,乘積末尾有,0,時(shí)，要先點(diǎn)上小數(shù)點(diǎn)，再去掉末尾的,0,哦！,1.,計(jì)算下面各題。,教材,P6,做一做 第,1,題,3.74.6 0.481.5,3.7,4.6,2 2 2,=17.02,0.4 8,1.5,2 4 0,4 8,7 2 0,=0.72,1 4 8,1 7 0 2,.,.,0,0.290.07 0.0560.15,0.2 9,0.0 7,=0.0203,0.0 5 6,0.1 5,2 8 0,5 6,8 4 0,=0.0084,2 0 3,.,.,易錯(cuò)點(diǎn)：注意積中的小數(shù)位數(shù)。,0 0,0 0 0,請(qǐng)總結(jié)一下，小數(shù)乘法的計(jì)算方法吧？,注意：,1.,積的位數(shù)不夠時(shí)，要添,0,占位，再點(diǎn)小數(shù)點(diǎn)。,2.,乘積末尾有,0,時(shí)，要先點(diǎn)上小數(shù)點(diǎn)，再去掉,末尾的,0,哦！,2.,教材,P6,做一做 第,2,題,2.4 =,3,5,1.5,1.1,1.2 =,0.4,0.11,0.35,0.9,7.2,12,3.6,2.64,0.48,0.132,0.42,1.08,分別比較積和第一個(gè)因數(shù)的大小，你能發(fā)現(xiàn)什么？,一個(gè)數(shù)（,0,除外）乘大于,1,的數(shù)，積比原來(lái)的數(shù)（）。,一個(gè)數(shù)（,0,除外）乘小于,1,的數(shù)，積比原來(lái)的數(shù)（）。,大,小,大于,1,小于,1,積小于另一個(gè)因數(shù),積大于另一個(gè)因數(shù),1.0625 0.0820.14,0.0 8 2,0.1 4,3 2 8,8 2,0.0 1 1 4 8,=0.01148,1.0 6,2 5,5 3 0,2 1 2,2 6.5 0,=26.5,1.,計(jì)算下面各題。,教材,P8,練習(xí)二,第,1,題,三、鞏固訓(xùn)練,270.43 0.0550.06,0.4 3,2 7,3 0 1,=11.61,0.0 5 5,0.0 6,3 3 0,=0.0033,0,.,.,.,.,0,0,.,8 6,1 1.6 1,1.,計(jì)算下面各題。,教材,P8,練習(xí)二,第,1,題,三、鞏固訓(xùn)練,7560.9 756 10.94 1,4.251.1 4.25 31.41.2 31.4,2.,在下面的,里填上,“”,或,“”,。,教材,P10,練習(xí)二 第,12,題,不計(jì)算，能直接說(shuō)出答案嗎？,6.253.2=20,（,cm,2,）,4.54.5=20.25,（,cm,2,）,4.235.9=24.957,（,cm,2,）,3.,計(jì)算下面各圖形的面積,。,（單位：,cm,）,教材,P9,練習(xí)二 第,9,題,3.2,6.25,4.5,4.5,4.23,5.9,路程,=,速度時(shí)間,70.5,3.4=239.7,（千米）,答：,他坐,汽車,的路程是,239.7,千米。,4.,哥哥,去,上大學(xué)要坐,3.4,小時(shí)的,汽車,，,汽車,的平均速度是,70.5,千米,/,時(shí)。他坐,汽車,的路程是多少千米？,教材,P10,練習(xí)二 第,11,題,5.,先調(diào)查下面這些水果的單價(jià)，再計(jì)算總價(jià)。,教材,P9,練習(xí)二 第,10,題,水果,單價(jià)（元,/,千克）,0.8kg,2.5kg,5kg,6.2kg,蘋(píng)果,香蕉,橘子,葡萄,小數(shù)乘小數(shù)（,2,）,注意：,1.,積的位數(shù)不夠時(shí)，要添,0,占位，再點(diǎn)小數(shù)點(diǎn)。,2.,乘積末尾有,0,時(shí)，要先點(diǎn)上小數(shù)點(diǎn)，再去掉末尾的,0,哦！,小數(shù)乘小數(shù)的計(jì)算方法：,一個(gè)數(shù)（,0,除外）乘大于,1,的數(shù)，積比原來(lái)的數(shù)（）。,一個(gè)數(shù)（,0,除外）乘小于,1,的數(shù)，積比原來(lái)的數(shù)（）。,大,小,四、課堂小結(jié),1.,從課后習(xí)題中選??；,2.,完成練習(xí)冊(cè)本課時(shí)的習(xí)題。,五、課后作業(yè),一、想一想，填一填。,選自,創(chuàng)優(yōu)作業(yè),100,分,0.1 8,0.0 6,（）,0.0 1 0 8,1.,先按照整數(shù)乘法算出（）,（）的積，再點(diǎn)（）。,兩,（）位小數(shù),（）位小數(shù),（）位小數(shù),兩,四,18,6,小數(shù)點(diǎn),六、鞏固練習(xí),一、想一想，填一填。,選自,創(chuàng)優(yōu)作業(yè),100,分,0.1 8,0.0 6,（）,0.0 1 0 8,兩,（）位小數(shù),（）位小數(shù),（）位小數(shù),兩,四,2.,兩個(gè)因數(shù),0.18,和,0.06,中一共有（）位小數(shù)，就從積的（）邊起數(shù)出（）位，點(diǎn)上小數(shù)點(diǎn)。,四,右,四,六、鞏固練習(xí),一、想一想，填一填。,選自,創(chuàng)優(yōu)作業(yè),100,分,0.1 8,0.0 6,（）,0.0 1 0 8,兩,（）位小數(shù),（）位小數(shù),（）位小數(shù),兩,四,3.,乘得的積的小數(shù)位數(shù)不夠時(shí)，要在（）面用（）補(bǔ)足，再點(diǎn)上小數(shù)點(diǎn)。,前,0,六、鞏固練習(xí),二、列豎式計(jì)算。,選自,創(chuàng)優(yōu)作業(yè),100,分,0.450.12=,0.0650.34=,0.4 5,0.1 2,9 0,.,4 5,5 4 0,0.054,0.0 6 5,0.3 4,2 6 0,1 9 5,2 2 1 0,.,0.0221,0 0,0 0,0.360.055=,0.0850.24=,0.3 6,0.0 5 5,1 8 0,1 8 0,1 9 8 0,.,0.0 8 5,0.2 4,3 4 0,1 7 0,2 0 4 0,.,0.0198,0.0204,0 0,0 0,