大家知道,整数和分数合称有理数,无限不循环小数叫无理数;一切有理数都可表成分数 p/q(p、q 互质,p∈N,q∈N),无理数不能表示成分数 p/q。那么,将分数 p/q 化为小数,是有限小数,还是无限循环小数呢?小数的位数或循环节内的数字的个数又是多少呢?本文试图对这两个问题作一些一般性的探讨,供小学数学老师教学这个内容时参考。 We all know that integers and fractions together called rational numbers, infinite non-recurring decimal called irrational number; all rational numbers can be expressed as the fraction p / q (p, q mutual prime, p∈N, q∈N), irrational number can not be expressed as the number of p / q. Then, the fraction p / q into decimals, is a finite fraction, or an infinite loop fraction? Number of decimal places or the number of cycles and what is the number? This article attempts to make some generality on these two issues For discussion, primary school mathematics teacher teaching this content reference.