Why does my child think √9 is irrational?
Your child counts every square root as irrational, such as √9, which is 3.
Why children do it
The roots they meet as irrational, √2 and √5, make every root look that way. But a root of a square number is a whole number: √9 is 3, and 3 can be written as 3/1, so it's rational. Working out each root first sorts them.
How to help at home
Ask them to work out each root first: √9 is 3, a whole number, so it's rational.
The right way
How many of these are irrational: √4, 1/3, √5, π, √9?
- 2√4 = 2, √9 = 3 and 1/3 are rational; √5 and π are irrational.
Find out where your child is
A free maths check, in about 15 minutes, shows what your child knows and the mistakes they make. No sign-up.
Start the free checkRelated mistakes
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