小數(shù)豎式計(jì)算要點(diǎn)

1、一個(gè)數(shù)除以小數(shù)例題解析及知識(shí)要點(diǎn)一個(gè)數(shù)除以小數(shù)例題解析及知識(shí)要點(diǎn)豎式計(jì)算思路保證商不變商不變的前提下，使除數(shù)變成整數(shù)除數(shù)變成整數(shù)，利用商不變規(guī)律商不變規(guī)律，將除數(shù)變成整數(shù)，除數(shù)擴(kuò)大了多少倍，被除數(shù)也同時(shí)擴(kuò)大多少倍，（除數(shù)小數(shù)點(diǎn)向右移動(dòng)幾位，被除數(shù)小數(shù)點(diǎn)也同時(shí)向右移動(dòng)幾位）具體計(jì)算方法除數(shù)是小數(shù)的除法計(jì)算方法：除數(shù)是小數(shù)的除法計(jì)算方法：①移動(dòng)除數(shù)的小數(shù)點(diǎn)，使它變成整數(shù)；移動(dòng)除數(shù)的小數(shù)點(diǎn)，使它變成整數(shù)；②除數(shù)的小數(shù)點(diǎn)向右移動(dòng)幾位，被除數(shù)的小

2、數(shù)點(diǎn)也向右移動(dòng)幾位（位數(shù)不夠的，在被除數(shù)的末尾用除數(shù)的小數(shù)點(diǎn)向右移動(dòng)幾位，被除數(shù)的小數(shù)點(diǎn)也向右移動(dòng)幾位（位數(shù)不夠的，在被除數(shù)的末尾用“0”補(bǔ)足）補(bǔ)足）；③按照除數(shù)是整數(shù)的小數(shù)除法進(jìn)行計(jì)算。按照除數(shù)是整數(shù)的小數(shù)除法進(jìn)行計(jì)算。例1、7.0040.68004.768.0680.68.7.00.410.22042040680.68.7.00.410.22042040本題點(diǎn)評本題點(diǎn)評：本題三個(gè)關(guān)鍵點(diǎn)：1、因?yàn)槌龜?shù)是小數(shù)，所以必須移動(dòng)小數(shù)點(diǎn)，使除數(shù)

3、變整數(shù)使除數(shù)變整數(shù)，同時(shí)被除數(shù)也要移動(dòng)相同的位數(shù)，這樣保證商不變，這是所有除數(shù)是小數(shù)的都必須進(jìn)行的步驟；（左邊紅框）2、遇到不夠除時(shí)，要注意商0，而不是急著把下一個(gè)數(shù)字放下來，也不能急著添0（右邊紅框第三步）3、除到個(gè)位點(diǎn)上點(diǎn)，只要除到了個(gè)位，就要在個(gè)位的右邊點(diǎn)上小數(shù)點(diǎn)（右邊紅框第四步）除數(shù)是一位小數(shù)，要擴(kuò)大100倍，除數(shù)除數(shù)小數(shù)點(diǎn)向右移小數(shù)點(diǎn)向右移動(dòng)2位，被除被除數(shù)小數(shù)點(diǎn)同時(shí)數(shù)小數(shù)點(diǎn)同時(shí)也向右移動(dòng)也向右移動(dòng)2位。劃掉之前的小數(shù)點(diǎn)和沒用

4、的00.68.7.00.40.68.7.00.40.68.7.00.40.68.7.00.4最后十分位上商3，檢查檢查此時(shí)被除數(shù)的小被除數(shù)的小數(shù)點(diǎn)與商的小數(shù)點(diǎn)與商的小數(shù)點(diǎn)是否對齊數(shù)點(diǎn)是否對齊把4放下來除到個(gè)除到個(gè)位點(diǎn)上位點(diǎn)上點(diǎn)，點(diǎn)上小數(shù)點(diǎn)20除以68不夠除，不夠除，夠除，要商要商0試商1，有余數(shù)2把0放下來680.68.7.00.4120680.68.7.00.4120680.68.7.00.41020680.68.7.00.41020

5、680.68.7.00.410.20680.68.7.00.410.20680.68.7.00.410.204680.68.7.00.410.204680.68.7.00.412680.68.7.00.412680.68.7.00.410.32042040680.68.7.00.410.32042040再按照除數(shù)是整數(shù)的小數(shù)除法計(jì)算先移動(dòng)除數(shù)和被除數(shù)小數(shù)點(diǎn)先移動(dòng)除數(shù)和被除數(shù)小數(shù)點(diǎn)例3、2162.7再按照除數(shù)是整數(shù)的小數(shù)除法計(jì)算先移動(dòng)除數(shù)

6、和被除數(shù)小數(shù)點(diǎn)先移動(dòng)除數(shù)和被除數(shù)小數(shù)點(diǎn)2.72162.7216除數(shù)是一位小除數(shù)是一位小數(shù)，但被除數(shù)數(shù)，但被除數(shù)是整數(shù)是整數(shù)，看不到它的小數(shù)點(diǎn)，所以要先點(diǎn)出先點(diǎn)出被除數(shù)的小數(shù)被除數(shù)的小數(shù)點(diǎn)再同時(shí)把除數(shù)除數(shù)和被除數(shù)的小和被除數(shù)的小數(shù)點(diǎn)數(shù)點(diǎn)向右移動(dòng)向右移動(dòng)一位一位，有空缺的數(shù)位，有空缺的數(shù)位，用0補(bǔ)足補(bǔ)足劃掉之前的小劃掉之前的小數(shù)點(diǎn)數(shù)點(diǎn)2.7.216.0.2.7.216.0.2.7216.2.7216.2.7.216..2.7.216..2.

7、7.216.0.2.7.216.0.2162.7.216.0.802162.7.216.0.80除數(shù)除數(shù)2位看位看被除數(shù)前被除數(shù)前2位，位，2位不夠看位不夠看3位，位，216216夠除，商夠除，商8，寫在寫在6上面。上面。余數(shù)剛好為余數(shù)剛好為002162.7.216.0.8002162.7.216.0.800被除數(shù)末被除數(shù)末尾的尾的0不往下掉，不往下掉，而往上提，而往上提，即：即：商0商0此時(shí)已經(jīng)除盡已經(jīng)除盡，商還在整數(shù)范圍商還在整數(shù)范

8、圍，不需要除到小數(shù)部分，所以商的商的小數(shù)點(diǎn)可以不點(diǎn)出來小數(shù)點(diǎn)可以不點(diǎn)出來，但要知道商的小數(shù)點(diǎn)是商的小數(shù)點(diǎn)是“隱藏隱藏”在0的后面的后面。和被除數(shù)的小數(shù)點(diǎn)是對齊的和被除數(shù)的小數(shù)點(diǎn)是對齊的。本題點(diǎn)評：本題三個(gè)關(guān)鍵點(diǎn)：本題點(diǎn)評：本題三個(gè)關(guān)鍵點(diǎn)：1、除數(shù)與被除數(shù)小數(shù)點(diǎn)的移動(dòng)除數(shù)與被除數(shù)小數(shù)點(diǎn)的移動(dòng)，本題出現(xiàn)了被除數(shù)小數(shù)的位數(shù)比除數(shù)的小數(shù)位數(shù)少被除數(shù)小數(shù)的位數(shù)比除數(shù)的小數(shù)位數(shù)少的情況（被除數(shù)是整數(shù)，0位小數(shù)，除數(shù)1位小數(shù)），這樣在移動(dòng)的過程中，就