It is my birthday today
Last year I had 5 candles
4 were lit the last was not
But today, I'll light them all
How old am I turning today?
HINT: I am not turning 5 today and...
Next year I'll have 6 candles, but I'll only light the first
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ME Ant
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4Hey, welcome to Puzzling! This is a good first puzzle but I highly recommend holding off on giving hints - often you'll find out you don't need them. – Deusovi May 11 '16 at 03:56
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17There's 10 kinds of people in the world. Those who understand binary and those who don't. – Johannes Pille May 11 '16 at 08:09
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5@JohannesPille and those who understand Gray code. – Pierre Arlaud May 11 '16 at 08:33
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42There are 10 kinds of people - those who understand ternary, those who don't, and those who mistake it for binary! – Alexander May 11 '16 at 09:18
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3Funny thing is, I catched this instant aswell, but by catching a hint that actually wasn't one.... I read "turing" ^^ – Zaibis May 11 '16 at 15:15
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We actually did this for my dad's birthday this year (he's a PhD in Comp Sci). – GreySage May 11 '16 at 19:18
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nice Binary.... – amanuel2 May 11 '16 at 22:30
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Kudos, @Alexander - well played Sir. However, as an aside, this game never ends: There's 10 kinds of people - those who understand quaternary, those who mistake it for ternary, those who think it's binary and those who think "Why is four ten?" – Johannes Pille May 12 '16 at 07:12
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2@Alexander I always heard this slightly different - there are 10 kinds of people - those who understand binary, and those who don't -- and those who didn't expect this to be a ternary joke. I like it this way because the unexpected part doesn't come until the end. – scholtes May 12 '16 at 22:06
4 Answers
100
You're turning
11111 (Or 31)! This is because you light your candles in binary: last year you turned 30 (11110) so you only lit the first four candles.
Deusovi
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@ᴊᴀᴠʏ Me too, but at same time we post; after a few mins we don't :) – Jonathan Allan May 11 '16 at 04:00
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1Is the LSB usually 'last' ? I guess the hint defines it, but it took the hint... – Lamar Latrell May 11 '16 at 05:19
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2@Lamar: Yes, just like the least significant digit is last in base ten. – Deusovi May 11 '16 at 05:20
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Some people (likely many) might call it 'last', others might not, others might see it as arbitrary :) – Lamar Latrell May 11 '16 at 05:21
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@LamarLatrell another thing to remember is that the LSB is going to change from year-to-year. If only one candle is changing (as we're told without the hint), it must be the LSB. – A N May 11 '16 at 18:08
40
Today you are turning
31
Since
you are lighting your candles in binary, $11110 = 30; 11111 = 31; 100000 = 32$
Jonathan Allan
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I've got a different solution, that is very close to the current one, but a little bit different. (and fits of course)
He is turning
30. Every candle that is lit stands for 6 years. Every candle that is not lit stands for 5 years. (5 candles lit is 5x6=30) And next year he becomes 31 (1 candle lit, 5 not. 1x6+5x5=31)
Fearsome Statue
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You're turning
31
Since the analogy is in
binary and the candles represent face values of the numbers,
you light the first 4
Next year you'll turn
32
and only light the first candle and not the other 5.
cst1992
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