- Definition
A rational number is any number that can be written as a simple fraction, like 1/2 or 3/4, where the bottom number isn't zero. This includes whole numbers, decimals that stop or repeat, and fractions themselves.
The whole number 8 is a rational number because it can be written as the fraction 8/1.
How to teach this in 30 seconds
Try this analogy: A rational number is like any amount of money you can hold, because it can always be written as a fraction of a dollar.
Ask your child: How could you write the decimal 0.25 as a fraction?
Common mix-up: Kids may think only numbers that look like fractions are rational. Any number that can be written as a fraction, including whole numbers, terminating decimals, and repeating decimals, is a rational number.
Examples
- The decimal 1.75 is rational because it can be written as the fraction 7/4.
- A negative number like -3 is rational because it can be written as -3/1.
- Even a repeating decimal like 0.333... is rational because it can be written as 1/3.
rational number is a term used in Ontario’s Kindergarten to Grade 8 curriculum.
Where this shows up
The descriptions on this page are SmartStudy’s own original, plain-language writing — not the Ministry’s wording. They are aligned to the Ontario Curriculum, © King’s Printer for Ontario. For the Ministry’s official wording, see the source link below. SmartStudy is an independent service and is not affiliated with, endorsed by, or sponsored by the Government of Ontario or the Ministry of Education. Ontario Curriculum and Resources ↗
