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'Good Approximations' printed from https://nrich.maths.org/
Why do this problem?
For a better understanding of rational and irrational numbers.
Possible approach
Use this problem as part of a lesson series on number to include some or all of:
- proof root 2 is irrational
- converting periodic decimals to rational numbers
- proof that every rational number has a periodic decimal expansion
- the rational numbers are countable (see Route to Infinity )
- the irrational numbers are uncountable (see the article Infinity is not a number ).
Key question
Why are the finite continued fractions which follow a regular pattern called 'convergents'?