5.04×2.1的積是________位小數(shù),11÷6的商用循環(huán)小數(shù)表示是________,精確到十分位是________.
三

1.8
分析:(1)要求5.04×2.1的積是幾位小數(shù),因?yàn)?.04與2.1末尾數(shù)相乘的末尾不是0,所以,5.04×2.1的積的小數(shù)位數(shù)就是5.04與2.1這兩個(gè)因數(shù)的小數(shù)位數(shù)和;
(2)根據(jù)小數(shù)的除法計(jì)算方法進(jìn)行計(jì)算,用循環(huán)小數(shù)表示出來,再用四舍五入法求近似數(shù)即可.
解答:根據(jù)題意可得:
(1)5.04是兩位小數(shù),2.1是一位小數(shù);
4×1=4;
2+1=3;
所以,5.04×2.1的積是三位小數(shù);
(2)11÷6=

;

≈1.8.
故答案為:三,

,1.8.
點(diǎn)評:積的小數(shù)位數(shù)等于兩個(gè)因數(shù)小數(shù)位數(shù)和,注意末尾數(shù)相乘是0的;求循環(huán)小數(shù),要計(jì)算出三個(gè)循環(huán)節(jié);再用四舍五入法求近似數(shù).