Math Dictionary / Irrational Number
Irrational Number
An irrational number cannot be written as a fraction of two integers.
Number SystemGrade 8Algebra 1SATACT
What it means
Its decimal form does not end and does not repeat in a pattern.
Also called: non-repeating decimal
Examples
| sqrt(2) is irrational |
| pi is irrational |
| 0.121121112… can be irrational if it never repeats |
Common mistake
A long decimal is not automatically irrational. Repeating decimals are rational.
Try one
Question: Is sqrt(49) irrational?
Show answer
No. sqrt(49) = 7, and 7 is rational.