Poll of the Day > Can you solve this math problem?

(+) Yeah! (+)

If the last diget of this number becomes the first diget, the resulting number is exactly twice as large. What is the smallest number with this property?

Positive numbers only
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Ok well it has to be an even number
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10x+y=20y+2x

Nailed it.
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Lokarin posted...

10x+y=20y+2x

Nailed it.

Nope

You failed now must be executed
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12, I think?
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MasterSword546 posted...

12, I think?

12x2=24
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I'm betting this isn't an integer :/
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Junpeiclover posted...

I'm betting this isn't an integer :/

It is, kinda cheating not using whole numbers
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0 is twice as large as 0. 1x0 = 2x0

QED
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I can solve it if you pay me to.
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I could do that but I don't wanna
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Ogurisama posted...

MasterSword546 posted...

12, I think?

12x2=24

Yeah nevermind realised that right after i posted lol
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Holy shit the answer takes 10 minutes to explain o.O

https://www.youtube.com/watch?v=1lHDCAIsyb8
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0, if you want to be pithy.
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mastermix3000 posted...

Holy shit the answer takes 10 minutes to explain o.O

https://www.youtube.com/watch?v=1lHDCAIsyb8

Thats the video where i found the question

I wanted to see if anyone could get it here without looking it up.
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Lmfao the answer is absurd, you successfully trolled me

Answer for the lazy

105,263,157,894,736,842
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It would be a long process to figure it out.

First number would be a 1, last number a 2.

Second number has to be 0 (because 05 doubled is 1).

Third number then needs to be a 5.

So far we have 1052.....but 2105 is not 1052 doubled (Although it's close...at 2104). You would need to keep adding numbers to eventually get the right answer and I have no intention of doing all that work, especially in my head).

Basically though if you did want to, you could keep going until you finally found your answer.
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In their example 102 becomes 210.... I would have never solved it because as described a 102 woulda became a 201 on my end.
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Well blah, by the time I posted mine others had answered it already, but at least my brief answer was right (just not complete).

Glad I didn't freaking work it all out if it's that long though.
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You did an extremely poor job of explaining the problem. You needed at least an example of what the number becomes. I was thinking if you, for example, started with 1234, it would become 4231, or maybe 4234. Just saying "the last digit becomes the first digit" is ambiguous.
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Blaqthourne posted...

You did an extremely poor job of explaining the problem. You needed at least an example of what the number becomes. I was thinking if you, for example, started with 1234, it would become 4231, or maybe 4234. Just saying "the last digit becomes the first digit" is ambiguous.

Made sense to me and the solution seems easy as well. Not sure why it took a video 10 minutes or whatever they said above to explain it.

Last digit has to be 2x the first digit and you want the lowest possible combo so that means 1 and 2. You just need to keep adding digits after the 1 that will double into the previous digit.

So starting with 1, you need a 05 (for .5x2=1). So that gives you 105. To get the 5 you need to double 2.5 so that means the next digit is 2 and to get 2 you .1 (already have .5), so the next digit is 6 etc etc until you finally get all the digits I could figure it out in here in like 3 minutes probably. It's not hard and an elementary school kid that knows his multiplication tables could solve it. (and you can describe it in less then a minute).
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wolfy42 posted...

Blaqthourne posted...

You did an extremely poor job of explaining the problem. You needed at least an example of what the number becomes. I was thinking if you, for example, started with 1234, it would become 4231, or maybe 4234. Just saying "the last digit becomes the first digit" is ambiguous.

Made sense to me and the solution seems easy as well. Not sure why it took a video 10 minutes or whatever they said above to explain it.

Last digit has to be 2x the first digit and you want the lowest possible combo so that means 1 and 2. You just need to keep adding digits after the 1 that will double into the previous digit.

So starting with 1, you need a 05 (for .5x2=1). So that gives you 105. To get the 5 you need to double 2.5 so that means the next digit is 2 and to get 2 you .1 (already have .5), so the next digit is 6 etc etc until you finally get all the digits I could figure it out in here in like 3 minutes probably. It's not hard and an elementary school kid that knows his multiplication tables could solve it. (and you can describe it in less then a minute).

Ya, I interpreted the problem as the first and last digits swapping, not the last digit being shifted to the front.
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wolfy42 posted...

Made sense to me

So you interpreted it the way the problem author meant. I, as well as at least Lokarin, did not.
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Oh, and in case it wasn't obvious, you keep going till the number you need to multiply is 2 (you end with a 2). After the 6, you need a 3, to get 3 you need 1.5 etc etc...until eventually you reach a point where the number doubled is 2...and that is your solution. It's easy and fast, although it would be a pain to keep track of in your head (but if you typed it out, not so bad).
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I didn't understand the question.
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RFC22 posted...

I didn't understand the question.

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PMarth2002 posted...

RFC22 posted...

I didn't understand the question.

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