How to Tell That a Number Is Rational

By Leslie Renico
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The easiest way to tell if a number is rational or not is to attempt to express it as a fraction. If you can, then the number is rational. If not, then the number is irrational. According to Math Is Fun, the formal definition of a rational number is "a number that can be in the form p/q, where p and q are integers and q is not equal to zero." All integers are rational numbers, because they can be written as a fraction (for example, the integer 8 = 8/1). For decimals, though, the process takes a few steps.

About the Author

Leslie Renico's grant-writing career began in 2006 and her grants have brought in millions of dollars for nonprofits serving the poor and providing medical care for the needy. Renico has appeared on television and her articles have appeared in various online publications. She graduated from Saginaw Valley State University with a Bachelor of Arts in criminal justice in 1997.