# Is 0.999...=1 ? **URL:** \ **Category:** Factual Questions\ **Created:** [April 4, 2000, 2:32pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990 "2000-04-04T14:32:00Z")\ **Posts on this page:** 12\ **Page:** 4
**Author:** ![dragonfly98](https://avatars.discourse-cdn.com/v4/letter/d/7bcc69/32.png) [@dragonfly98](https://boards.straightdope.com/u/dragonfly98)\ **Post date:** [April 7, 2000, 11:54pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990/61 "2000-04-07T23:54:00Z")
> [@](#): > > Originally posted by kbutcher: > isn’t 1/9=.111… > and 2/9=.222… > > and so on, so > > 5/9 + 4/9 = .9999 or 9/9 > > and 9/9 IS = 1 > > Is this proof assuming anything wrong about the numbers? Bingo! 🆒 * * * -What’s right is only half of what’s wrong- George Harrison - _Old Brown Shoe_ ---
**Author:** ![Silo](https://avatars.discourse-cdn.com/v4/letter/s/ac91a4/32.png) [@Silo](https://boards.straightdope.com/u/Silo)\ **Post date:** [April 7, 2000, 5:49am UTC](https://boards.straightdope.com/t/is-0-999-1/10990/62 "2000-04-07T05:49:00Z")
Blah, Blah, Blah… You say .999… , well the dot,dot,dot is infinity and this infinite-ness converges to 1 by the statement (.999…). If you have not taken Calculus (at the least) then don’t respond to the post. SOME people here clearly don’t know what there talking about. .999… (is equivelent to)=1 and (.333…)^2 or (.333…)x3=.999…=1 If you don’t understand the logic behind this take some math classes. * * * If at first you don’t succeed you’re about average. ---
**Author:** ![Kamino\_Neko](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kamino_neko/32/34_2.png) [@Kamino\_Neko](https://boards.straightdope.com/u/Kamino_Neko)\ **Post date:** [April 7, 2000, 6:56am UTC](https://boards.straightdope.com/t/is-0-999-1/10990/63 "2000-04-07T06:56:00Z")
> [@](#): > > Originally posted by Silo: > \*\*(.333…)^2 or (.333…)x3=.999…=1 > \*\* (.333…)^2 is not the same as (.333…)\*3 (which is equal to 1). (.333…)^2 is the same as (.333…)\*(.333…), or 0.111… * * * _Eschew Obfuscation_ ---
**Author:** ![Silo](https://avatars.discourse-cdn.com/v4/letter/s/ac91a4/32.png) [@Silo](https://boards.straightdope.com/u/Silo)\ **Post date:** [April 7, 2000, 8:00am UTC](https://boards.straightdope.com/t/is-0-999-1/10990/64 "2000-04-07T08:00:00Z")
Whoops, you’re absolutely correct Tengu, I don’t know where my mind was. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [April 24, 2000, 1:35pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990/65 "2000-04-24T13:35:00Z")
I am just finding time to return to this debate, and I see it appears that Mr. Administrator cannot handle critism! He has conveniently deleted his postings as well as my rebuttals! So, if you can’t beat 'em, censor 'em! OK, well, to reiterate and summarize: Given: a) x = 0.9999… b) 10x = 9.9999… The Administrator concluded that this yields that, by subtraction, 9x = 9 thus x=1 Which proved x\<\>x…which cannot be! I contended that this was math chicanery and he was using methods of solving simultanteous equations when he does NOT have two independent (simultaneous) equations! If graphed, you’d find that equations (a) and (b) above yield parallel lines! Thus, I argued you could pick 8x instead of 10x and get yet still a different value! This is typical of dependent equations. For those who understand matrices, I also challenged the Administrator to give me the value of the determinant for his set of equations. He failed to do this because if one were to try to write the determinant, they’d find that the value is indeterminant! Also, I challenged him to show a long division showing how 1/1=0.99… which he failed to do as well. Finally, for the record, for those still unsure: 1/3 + 1/3 + 1/3 = 1 0.33… + 0.33… + 0.33… = 1.0 \<\> 0.99… Moral of this story! Don’t fall for math chicanery! (They’ll also try to show you how 1=2) * * * “They’re coming to take me away ha-ha, ho-ho, hee-hee, to the funny farm where life is beautiful all the time… :)” - Napoleon IV ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [April 24, 2000, 1:40pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990/66 "2000-04-24T13:40:00Z")
> [@](#): > > Originally posted by neuro-trash grrrl: > \*\*I’m a math major! Let me through! > \*\* Math major, huh? …that’s scary! So, I suppose you expect one to find the last decimal place of pi in this manner? C’mon! The essence of repeating value is the fact that it does not end. It could not be printed on a banner as you suggest unless the banner were infinitely long! So, because pi cannot be expressed on a banner of finite value, I should just truncate it until it does fit? What size banner would I pick to your liking? * * * “They’re coming to take me away ha-ha, ho-ho, hee-hee, to the funny farm where life is beautiful all the time… :)” - Napoleon IV ---
**Author:** ![C\_K\_Dexter\_Haven](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@C\_K\_Dexter\_Haven](https://boards.straightdope.com/u/C_K_Dexter_Haven)\ **Post date:** [April 24, 2000, 1:51pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990/67 "2000-04-24T13:51:00Z")
Hey, Jinx, I had nothing to do with the deletion of posts between 4/07 and 4/24. They were there last night. I will check with our tech staff and see if we can resolve this, I’m baffled. As a matter of principle: I don’t delete posts unless they are in clear violation of rules. I have never deleted a huge hunk of posts, and see no reason that I ever would. I’m hoping this is some sort of recoverable technical hiccough. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [April 24, 2000, 2:00pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990/68 "2000-04-24T14:00:00Z")
1000 apologies to the Administrator. :o It seemed too coincidental to be just an electronic blip. * * * “They’re coming to take me away ha-ha, ho-ho, hee-hee, to the funny farm where life is beautiful all the time… :)” - Napoleon IV ---
**Author:** ![C\_K\_Dexter\_Haven](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@C\_K\_Dexter\_Haven](https://boards.straightdope.com/u/C_K_Dexter_Haven)\ **Post date:** [April 24, 2000, 3:11pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990/69 "2000-04-24T15:11:00Z")
OK, now I’m good and confused. There are two simultaneous threads on this subject… see also [Math: .99repeating = 1?](http://boards.straightdope.com/ubb/Forum3/HTML/007496-2.html) Are we getting confused about which thread is which? Is it possible stuff din’t disappear at all, but was in the other thread? Can we agree to keep the posts in that other thread, and close this one? ---
**Author:** ![JonF](https://avatars.discourse-cdn.com/v4/letter/j/cab0a1/32.png) [@JonF](https://boards.straightdope.com/u/JonF)\ **Post date:** [April 24, 2000, 4:54pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990/70 "2000-04-24T16:54:00Z")
I think Jinx has indeed confused the thereads. I replied to exactly his point (in more detail) in the other thread. Briefly, Jinx, you analyzed an invalid system of equations which is not the system proposed. The “system of equations” is one equation in one unkown. Adding a multiple of an equation to itself is a valid manipulation of the system (provided that the multiplier is not -1). The coefficient matrix of the system is {1}, and it is not difficult to calculate that the determinant is 1. ---
**Author:** ![Monty](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/monty/32/47_2.png) [@Monty](https://boards.straightdope.com/u/Monty)\ **Post date:** [April 25, 2000, 5:08am UTC](https://boards.straightdope.com/t/is-0-999-1/10990/71 "2000-04-25T05:08:00Z")
> [@](#): > > Originally posted by CKDextHavn: > As a matter of principle: I don’t delete posts unless they are in clear violation of rules. Gee, Dext; but all the “evidence” against .9(repeating) = 1 does violate math rules. ---
**Author:** ![manhattan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manhattan/32/7_2.png) [@manhattan](https://boards.straightdope.com/u/manhattan)\ **Post date:** [April 24, 2000, 7:25pm UTC](https://boards.straightdope.com/t/is-0-999-1/10990/72 "2000-04-24T19:25:00Z")
Is someone has an objection to me closing this thread and confining discussion to the other thread on this subject (located [here](http://boards.straightdope.com/ubb/Forum3/HTML/007496-2.html) ), please let me know in the next day or so. [Previous page](https://boards.straightdope.com/t/is-0-999-1/10990.md?page=3)