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Here's a puzzle that a teacher told me today:

How can you cut twelve in half and get seven?

Hint (only if you're stumped):

Don't let just regular numerals control you

Another Hint

Notice that I didn't use the math tag

Quark
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michaelpri
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9 Answers9

66

Here's a more mathematical answer from a programmer:

If we use the base 12 numbering system then 12 (in base 12) == 14 (in base 10), and half of that is 7 (in both base 10 and 12).

PolyTekPatrick
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    Although I think the expected (and now accepted) answer is the Roman Numerical one, I actually like your answer better. +1 from me. – BmyGuest Jan 24 '15 at 10:35
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    12 (in base 12 (in base 10)) :P – user253751 Jan 24 '15 at 11:24
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    But the body of the question explicitly spells out t-w-e-l-v-e and s-e-v-e-n. – 200_success Jan 25 '15 at 11:13
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    @200_success In numeration systems (which happens to be my field of study), we often use "eleven" for what is written as "11" in the base we work in, so "twelve" need not be 2*6 always :) – yo' Jan 25 '15 at 19:17
54

Slice XII across the middle to get VII.

I'm pretty sure that's what Quark's answer is facetiously alluding to.

Daniil Agashiyev
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Cut perfectly in half we have a 7 folks!

Cut perfectly in half we have a 7!

Trang Oul
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41

Slightly different answer:

12 is a base ten number. Cut the base in half, and you get 7.
(base five) 12 = (base ten) 7

Nick ODell
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21

Here's how you can get seven by cutting twelve in half:

enter image description here

Quark
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11

This is 12 points:

. . . .
. . . .
    . .
    . .

Cutting it diagonally from top right to bottom left, we get two sets of 7 points:

. . . .
. . . 

and:

  .
. .
. .
. .
cst1992
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11

@CoolGuy I disagree that it isn't cutting "12" in half. No matter which of the resulting fragments you take, you get 7.

Lines in PS are to ensure that they are exactly (100/100 pixels above and below guide lines) cut in half.

12 / 2 = 7

Trang Oul
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March Ho
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0

Using roman numbering seems to do the trick : 12 is : XII, cut it horizontally and you have VII at the top

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Uriel
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-1

12 = XII

strike through the middle

the top half now becomes VII

VII = 7

Mohit Jain
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