All Big Issues
The Instigator
Pro (for)
Winning
114 Points
The Contender
Con (against)
Losing
41 Points

# .999... is exactly equal to 1

Do you like this debate?NoYes+13

Post Voting Period
The voting period for this debate has ended.
after 28 votes the winner is...
Biowza
 Voting Style: Open Point System: 7 Point Started: 9/14/2008 Category: Science Updated: 9 years ago Status: Post Voting Period Viewed: 28,247 times Debate No: 5388
Debate Rounds (3)

99 comments have been posted on this debate. Showing 1 through 10 records.
Posted by tlt 1 year ago
this is an ongoing debate between me and my children and this debate has occupied the time for many hours on road trips. I say it is not the same . my reasoning is simple fractions and decimals are not the same. A fraction breaks a whole into equale parts and decimals break down numbers. so if I take a pizza and divide it in thirds and eat 1 third each day my pizza is gone. 33.333....X 3= 99.9999999999999...
i would never get my pizza eaten.
Posted by Hal314 5 years ago
An interesting website discussing this topic in great detail is at:

Posted by mjs1138 5 years ago
There is a common misconception that .999...is equal to 1, created by proofs such as the one below:

1/3 = .333...

3 (1/3) = 3 (.333...)

1 = .999...

The flaw in this proof is that 1/3 is not actually equal to .333... because division is never completed: part of 1/3 is always in a remainder and never appears in the quotient.
Posted by erik150x 5 years ago
Please excuse spelling below, I posted from my smartphone.
Posted by erik150x 5 years ago
Arguments which say .999... X 10 = 9.999... Are not neccessarly true, I would say wrong.

.99 x 10 = 9.90 and NOT 9.99

But people want to say:
.999... x 10 = 9.999...(9) instead of 9.999...(0)

Now you can say 9.999...(0) doesn't make sense or exist, I'll grant that.
But you also can't throw in an extra ...(9) or in other words 'infinitely small amount' and pretend like you didn't.

1/3 is not .333... It is .333... + ....(1/3000...)
Do the math your self, always a remainder.

Proofs that unvolve geometric series, make use of the limit process which in my mind basically assume 1/infinity = 0. This is the founding principle of calculus, but with fancy words not saying so. Basically calculus says... Let's assume 1/infinity = 0. Which for practical applications may be fine, but it doesn't make it an abdolute truth, you can't use calculus yo prove .999... = 1, because tje assumption is built in.

Posted by Qynze 6 years ago
Hehe...infinity minus 1 is still infinity, I suppose...
Posted by xiaotianZ 8 years ago
hahaha! nice! i like this math debate! as soon as the pro came up with solid evidence of math he won. nice! i love math and this debate gives me the shivers!
Posted by Metz 9 years ago
Ok I realize this is an Old debate but if .999=1 then

.999=99.9%
If a study is taken about whether 1000 people agree or disagree with X and 999 say they agree and one says they do not the numbers look like this: 999/1000 and 1/1000. In decimal Form that is .999 and .001
1=100% and 99.9%=100% as I demonstrated in the above example.... Thus .999 does not always equal 1
Posted by A.Roche 9 years ago
I am sorry, I retract my previous comment and I accept that 0.9 recurring is in fact equal to 1. After actually thinking about it a little, I now concur with the pro. The moral of this story is "think before you speak" haha.

haha, I'd like to thank Logical-Master, Ragnar_Rahl and CoronerPerry for their sharp, albeit humbling comments in response to mine, plus they are correct in this case, so please listen to them!

Quite frankly, I wish comments could be deleted from these debates, as I'd certainly like to delete mine!
Posted by Ragnar_Rahl 9 years ago
"A.Roche, then how come 1/3 multiplied by 3/1 = 1 1/3, as we know is represented by .333333..."

The assumption that .33333... =1/3 is fundamentally the same assumption as that .999999.... = 1. As such, that "proof" is circular, though valid ones exist :D
28 votes have been placed for this debate. Showing 1 through 10 records.