The Math Forum

Ask Dr. Math - Questions and Answers from our Archives
Associated Topics || Dr. Math Home || Search Dr. Math

Is 0.99 Periodical Equal to 1?

Date: 25 Apr 1995 06:26:53 -0400
From: Karsten Koops
Subject: 0,999. = 1 ?

Hello there!
Today I had a discussion with my collegues about whether 0,99. periodically
is the same value as 1. My statement is:

     Suppose                           X = 0,99. periodical
     Multiply by 10, so you get       10X=9,99.
     Subtract 1X (0,99.)               9X=9
     Divide by 9 and you get            X=1

Is this equation and therefore the above statement correct?
By the way, could you tell me, who is/are DR.MATH and SWARTHMORE?
Thanks much, bye KOOPS@MAGNET.AT
--- OffRoad 0.99o unregistered

Date: 25 Apr 1995 09:41:27 -0400
From: Dr. Ken
Subject: Re: 0,999. = 1 ?

Hello there!

Yes, that's exactly right.  Another way to show it is that if 1 and
0,9999... were two different numbers, you'd be able to find numbers in
between them, but you can't.

The Dr.s of math are undergraduate students at Swarthmore College.
Swarthmore is a 4-year liberal arts college just south of Philadelphia, PA.  

Associated Topics:
High School Analysis

Search the Dr. Math Library:

Find items containing (put spaces between keywords):
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

Math Forum Home || Math Library || Quick Reference || Math Forum Search

Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.