Non-Periodic, Non-Terminating DecimalsDate: 06/26/2001 at 17:45:53 From: rebecca rocha Subject: Math (algebra) Why is a non-periodic, non-terminal decimal an irrational number? I have looked in math books at the library. Date: 06/27/2001 at 12:13:44 From: Doctor Ian Subject: Re: Math (algebra) Hi Rebecca, When you have a terminating decimal, like 0.234, that is just a shorthand way of writing 234/1000. So any terminating decimal is a rational number. When you have a repeating decimal, like 0.234234..., you can do this little trick: x = 0.234234... 1000x = 234.234234... 1000x - x = 234 999x = 234 x = 234/999 So any repeating decimal is a rational number. In short, to convert a decimal to a rational number, you have to be able to figure out what the denominator is. But unless the decimal terminates or repeats, there is no way to do this. Or to put it another way, if you want to make up a decimal that isn't a rational number, you'd better make sure that it doesn't terminate or repeat. Does this help? Write back if you'd like to talk about this some more, or if you have any other questions. - Doctor Ian, The Math Forum http://mathforum.org/dr.math/ |
Search the Dr. Math Library: |
[Privacy Policy] [Terms of Use]
Ask Dr. Math^{TM}
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/