Question

3.7×2.96的積是________位小數(shù)，0.57×0.049的積是________位小數(shù)．

Answer 1

三    五
分析：根據(jù)小數(shù)乘法的計算法則，先按照整數(shù)乘法的計算法則算出積，再看兩個因數(shù)一共有幾位小數(shù)，就從積的末尾數(shù)出幾位點上小數(shù)點．由此解答．
解答：3.7×2.96；
3.7是一位小數(shù)，2.96是兩位小數(shù)，所以乘積是三位小數(shù)；
0.57×0.049；
0.57是兩位小數(shù)，0.049是三位小數(shù)，所以乘積是五位小數(shù)．
故答案為：三，五．
點評：此題主要考查在小數(shù)乘法中積的小數(shù)位數(shù)與兩個因數(shù)的小數(shù)位數(shù)之間的關(guān)系，積的小數(shù)位數(shù)等于兩個因數(shù)小數(shù)位數(shù)的和．