[整理版]用简便方法计算小数乘法
【题目】:
用简便方法计算:
? 2.64×51.9,264×0.481;
? 9.16×1.53,0.053×91.6。
【题目】:
用简便方法计算:
? 9.8,99.8,999.8,9999.8,1;
? 9.75,99.75,999.75,9999.75,1.2。
【题目】:
用简便方法计算:
? 0.36×7.5,0.036×25;
? 3.12,31.2×9.9。
【题目】:
用简便方法计算:
? 2.64×51.9,264×0.481;
? 9.16×1.53,0.053×91.6。
【题目】:
用简便方法计算:
? 9.8,99.8,999.8,9999.8,1;
? 9.75,99.75,999.75,9999.75,1.2。 【解析】:
仔细观察题目结构和题中数据可知,这两道都是连加计算题,题中的前几个数都接近整
十、整百、整千、整万数,应采用“凑整”的方法计算比较简便。
? 9.8,99.8,999.8,9999.8,1
,10,100,1000,10000,0.2,0.2,0.2,0.2,1
,11110,0.2
,11110.2
? 9.75,99.75,999.75,9999.75,1.2
,10,100,1000,10000,0.25,0.25,0.25,0.25,1.2
,11110,0.2
,11110.2
《奥赛天天练》第5讲,巩固训练,习题1 【题目】:
用简便方法计算:
? 0.36×7.5,0.036×25;
? 3.12,31.2×9.9。 【解析】:
第?题中0.36与0.036有效数字相同,第?题中有效数字相同的两个数是3.12和31.2。
我们可以把题中任意一步乘法计算,利用积的变化规律进行恒等变形,使这两题可以运用乘
法分配律简便计算。
? 0.36×7.5,0.036×25
,0.36×7.5,0.36×2.5
,0.36×(7.5,2.5)
,0.36×10
,3.6
3.12,31.2×9.9 ?
,3.12,3.12×99
,3.12×(1,99)
,3.12×100
,312