A rational number is a number that is in the form of p/q, where p and q are integers, and q is not equal to 0. Some of the examples of rational numbers include 1/3, 2/4, 1/5, 9/3, and so on.
链接：https://www.google.com.my/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjO28L69aH-AhUnWGwGHXHMA44QFnoECBoQAw&url=https%3A%2F%2Fbyjus.com%2Fmaths%2Frational-numbers%2F&usg=AOvVaw0-IKBcZfuolshpOB6pbIMU
An irrational number is a type of real number which cannot be represented as a simple fraction. It cannot be expressed in the form of a ratio. If N is irrational, then N is not equal to p/q where p and q are integers and q is not equal to 0. Example: √2, √3, √5, √11, √21, π(Pi) are all irrational.
链接：https://www.google.com.my/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjmrN7z-qH-AhVpUGwGHX35AlIQFnoECBsQAw&url=https%3A%2F%2Fbyjus.com%2Fmaths%2Firrational-numbers%2F&usg=AOvVaw1HXyFAo-TI19eOlDoodZCa
所以，8/7 是 rational number。
总之，如果可以写成分数的整数或小数的数就是 rational number（也就是有理数），而不能化成分数的数就是 irrational number，所以 8/7就是分数，所以是rational number。
额外：0.333333…… 和 1.7320508 是 rational 或 irrational number？
链接：https://byjus.com/question-answer/identify-the-numbers-1-7320508-and-0-333-as-rational-or-irrational-numbers/
在数学中，有理数（rational number）是指可以表示成两个整数之比的数，而无理数（irrational number）则是不能被表示为两个整数之比的数。比如，2、-3/4、0和1/2都是有理数，而π和√2则是无理数。 8/7是一个有理数，因为它可以写成8除以7的形式，而8和7都是整数。 可参考： Rational and Irrational Numbers
