Question

2．計(jì)算小數(shù)加、減、乘、除，都要把小數(shù)點(diǎn)對(duì)齊．×（判斷對(duì)錯(cuò)）

Answer 1

分析 計(jì)算小數(shù)加減法時(shí)必須把小數(shù)點(diǎn)對(duì)齊，而計(jì)算小數(shù)乘除法時(shí)，就不一定把小數(shù)點(diǎn)對(duì)齊了；據(jù)此判斷為錯(cuò)誤．

解答 解：因?yàn)樵谟?jì)算小數(shù)乘法時(shí)，先按照整數(shù)乘法的法則算出積，再數(shù)因數(shù)中一共有幾位小數(shù)，就從得數(shù)的末位起數(shù)出幾位點(diǎn)上小數(shù)點(diǎn)；據(jù)此可知計(jì)算小數(shù)乘法時(shí)，小數(shù)點(diǎn)不一定對(duì)齊；同理計(jì)算小數(shù)除法時(shí)，小數(shù)點(diǎn)也不一定對(duì)齊；只有計(jì)算小數(shù)加減法時(shí)必須把小數(shù)點(diǎn)對(duì)齊．
故答案為：×．

點(diǎn)評(píng) 此題考查在小數(shù)四則運(yùn)算中，小數(shù)點(diǎn)的位置問題，切記只有計(jì)算小數(shù)加減法時(shí)才能把把小數(shù)點(diǎn)對(duì)齊．