Report Abuse. a rational number is one that can be expressed as a ratio of two integers (ex: 414 / 391) pi cannot be expressed this way (although there are rational approximations, the exact value is irrational).notthejake Â· 7 years ago.Thumbs up.1.eport Abuse. a rational number is one that can be expressed as a ratio of two integers (ex: 414 / 391) pi cannot be expressed this way (although there are rational approximations, the exact value is irrational). notthejake Â· 7 years ago. Thumbs up. 1.