News for hackers. Stuff that matters.

A comment on Is infinity an odd or even number? (2011). Parent comment

Re:Is infinity an odd or even number? (2011) by pxx on Tuesday May 02, 2023 @10:37AM (#35788152)
Assuming sqrt(2)/2 is one of the elements of your set between 0 and 1, there are! See https://en.m.wikipedia.org/wiki/Countable_set
[ Parent | on HN ]
Re:Is infinity an odd or even number? (2011) by jameshart on Tuesday May 02, 2023 @12:40PM (#35790283)
Sqrt(2)/2 can not be written as a decimal number.

A decimal number is a rational whose denominator is an integer power of 10.

[ Parent | on HN ]
Re:Is infinity an odd or even number? (2011) by zorgmonkey on Tuesday May 02, 2023 @02:21PM (#35791971)
No, any rational number with a denominator that has only the prime factors of 2 and 5 will have a finite and exact decimal representation in base 10.
[ Parent | on HN ]
Re:Is infinity an odd or even number? (2011) by jameshart on Tuesday May 02, 2023 @03:00PM (#35792496)
That's exactly the same thing as I said, using different words.

And anyway, is Sqrt(2)/2 such a number?

[ Parent | on HN ]
Re:Is infinity an odd or even number? (2011) by davrosthedalek on Tuesday May 02, 2023 @11:31PM (#35797551)
That's not quite what you have said. 3/2 does not have an integer power of 10 as the denominator, but can be written as a decimal. Of course, it can also be written as a fraction with a integer power, for example 15/10. (You are of course right on the 1/sqrt(2) issue)
[ Parent | on HN ]