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# Subtraction

64 replies to this topic

### #51 matt.lang

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Posted 23 May 2008 - 04:16 AM

Subtraction - Back to the River Crossing Puzzles
How many times can you subtract the number 2 from the number 32?

Spoiler for Solution

Once. Didn't even look at the spoiler. If it says something different it's wrong.
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### #52 matt.lang

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Posted 23 May 2008 - 04:18 AM

WARNING: the following answer is one of those "nitpicky" type answers, but I'm really just trying to inject some humor.

Several people have suggested that the answer is infinite because you can subtract 2 from 32 once (32-2 = 30), and then you can do it again (32-2=30), and then you can do it again...as many times as you want.

There's a flaw in this though - the question asks how many times YOU can subtract 2 from 32. It takes a discreet amount of time to do that calculation, although it is pretty quick. Given that the action takes a discreet amount of time, and YOU will only live for discreet amount of time, there is a limit to the number of times that YOU can subtract 2 from 32.

Assuming that a person devotes the rest of their life to doing just this:
It takes me about 2.5 seconds to say "thirty two minus two equals thirty" at a normal pace, but if you are a speed talker, or if you're doing it in your head, you can certainly do it faster. Even it's 1 second per transaction, it's unlikely that you'll live to be more than 150 years old, and anyone reading this riddle has to be at least 3 years old to actually be able to read it, so:
(150-3)years x 365.25days x 24hours x 60minutes x 60 seconds = 4,638,967,200 times.

So my answer to the question: roughly 4.5 billion times.

You have a very mathematical sense of humour =)
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### #53 kimg7

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Posted 08 June 2008 - 08:09 AM

A wise man once said:
"A dog who chases his tail will be busy"
(Frank<3)

As apparent by all the posts to this question, he was absolutely correct.

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### #54 zirionian

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Posted 17 June 2008 - 01:47 AM

it wouldn't matter because[32-2=30]or it could be[32-2=1],[32-2=3].you would still end up with one of the same #in it even if you were going as followed:32-2=30,30-2=28,and so forth.you should never create a math problem that will trigger your brain to where it can & will be confused!!!!thanks for reading this reply!!!!
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### #55 bwmeekin

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Posted 27 June 2008 - 10:43 PM

as many times as you want it will go in to negatives e.g -2 -4 -6
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### #56 my massive brain is sexy

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Posted 13 July 2008 - 12:37 AM

hehe, i like it =D
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### #57 sagekid

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Posted 13 July 2008 - 12:40 AM

Funny one hahaha
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### #58 sagekid

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Posted 13 July 2008 - 12:42 AM

it wouldn't matter because[32-2=30]or it could be[32-2=1],[32-2=3].you would still end up with one of the same #in it even if you were going as followed:32-2=30,30-2=28,and so forth.you should never create a math problem that will trigger your brain to where it can & will be confused!!!!thanks for reading this reply!!!!

You should always makes problems like this one it makes sure your brain is in good shape
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### #59 plan9fromarz

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Posted 18 July 2008 - 04:07 PM

only once per try.
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### #60 Trogdor

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Posted 31 July 2008 - 09:13 PM

When you eat one cookie your tummy is no longer empty. When you put in 1 book, the bag is no longer empty.
Geddit now?

Actually cookies take some time to reach the stomach so, you can probably eat more than 1.
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