posted by Kimberly .
I have to decide whether these are rational or irrational.
Can someone explain this to me?
Rational numbers are just fractions. The decimal expansion of fractions will either terminate or it will become periodic after a while.
This means that the number:
is not rational. The further you go in the decimal expansion, the more 1's will there be inbetween the sixes, so the digits will never repeat.
The two other numbers are, of course, rational.