Question

3.09×0.05的積有

四

位小數(shù)，4.2×3.76的積有

三

位小數(shù)．

Answer 1

分析：根據(jù)小數(shù)乘法的計(jì)算法則：先按照整數(shù)乘法的計(jì)算法則算出積，再看兩個(gè)因數(shù)一共有幾位小數(shù)，就從積的右邊起數(shù)出幾位點(diǎn)上小數(shù)點(diǎn)．據(jù)此解答．

解答：解：根據(jù)小數(shù)乘法的計(jì)算法則可知：積的小數(shù)位數(shù)等于兩個(gè)因數(shù)小數(shù)位數(shù)的和．
所以，3.09×0.05的積有四位小數(shù)；
4.2×3.76的積有三位小數(shù)；
故答案為：四，三．

點(diǎn)評(píng)：此題考查的目的是掌握小數(shù)乘法的計(jì)算法則，明確：積的小數(shù)位數(shù)等于兩個(gè)因數(shù)小數(shù)位數(shù)的和．