【答案】:
10.5
1.05
0.105
0.0105
0.0105
發(fā)現(xiàn):兩個(gè)乘數(shù)相乘,一個(gè)乘數(shù)不變,另一個(gè)乘數(shù)的小數(shù)點(diǎn)向左(或向右)移動(dòng)幾位,積的小數(shù)點(diǎn)也向左(或向右)移動(dòng)相同的位數(shù);如果兩個(gè)乘數(shù)的小數(shù)點(diǎn)都向左(或向右)移動(dòng),那么積的小數(shù)點(diǎn)移動(dòng)的位數(shù)是兩個(gè)乘數(shù)移動(dòng)位數(shù)的和。
【解析】:
1.4×7.5:先算14×75=1050,1.4有1位小數(shù),7.5有1位小數(shù),共2位小數(shù),積為10.5;
0.14×7.5:先算14×75=1050,0.14有2位小數(shù),7.5有1位小數(shù),共3位小數(shù),積為1.05;
0.14×0.75:先算14×75=1050,0.14有2位小數(shù),0.75有2位小數(shù),共4位小數(shù),積為0.105;
0.014×0.75:先算14×75=1050,0.014有3位小數(shù),0.75有2位小數(shù),共5位小數(shù),積為0.0105;
0.14×0.075:先算14×75=1050,0.14有2位小數(shù),0.075有3位小數(shù),共5位小數(shù),積為0.0105;
發(fā)現(xiàn):兩個(gè)乘數(shù)一共有幾位小數(shù),積就有幾位小數(shù)(當(dāng)積的末尾沒(méi)有0時(shí))。