XXIII
------- = II
VII
All you need to do is move one matchstick from the roman numerals to make the equation true.
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1$\begingroup$ move or remove? $\endgroup$– question_askerCommented Mar 15, 2016 at 18:55
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1$\begingroup$ @question_asker move... $\endgroup$– ABcDexterCommented Mar 15, 2016 at 18:56
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$\begingroup$ I remember this one from when I was a kid (40 odd years ago), great seeing it here! $\endgroup$– AbelCommented Feb 13, 2022 at 21:23
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4 Answers
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15
You could move...
The last I from the numerator onto the top of the result, like so:
XXII
---- = $\pi$
VII
It's an approximation, but yesterday was Pi Day.
answered Mar 15, 2016 at 19:02
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1$\begingroup$ @ttt it will always be yesterday relative to the posting of the question $\endgroup$ Commented Mar 15, 2016 at 20:05
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1$\begingroup$ @question_asker, I meant, if this question was asked 6 months from now, I don't think the answer would be correct since 22/7 does not equal pi. (6 months from now you wouldn't say, 22/7 = pi and pi day is March 14. At least I don't think I would say that...) $\endgroup$– TTTCommented Mar 15, 2016 at 20:09
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1$\begingroup$ @ttt but the question isn't posted six months from now, it was posted today $\endgroup$ Commented Mar 15, 2016 at 20:18
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2$\begingroup$ @TTT "Yesterday" will always be assumed to be "yesterday at the time of writing" (equal to the day before the post was written), and since these posts are all timestamped, there's no problem. $\endgroup$– jpmc26Commented Mar 15, 2016 at 23:07
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1$\begingroup$ @ABcDexter Please let's not. Though there is a fair point here somewhere about the possibility of leaving the relative date out entirely and otherwise obliquely hinting at it. $\endgroup$ Commented Mar 16, 2016 at 14:56
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If in “make the equation true” only the words make and true are taken literally:
XXII
—— ≠ II
VII
As quintopia points out, this is no longer an equation. (A deserved custard $\pi$ in my face.)
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2$\begingroup$ Well, that would go into the
lateral-thinkingpart ;-) $\endgroup$ Commented Mar 15, 2016 at 19:15 -
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1$\begingroup$ Is an inequality considered a equation? $\endgroup$ Commented Mar 17, 2016 at 17:53
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$\begingroup$ Too true, @quintopia, the answer now includes a duly credited disclaimer. (As a matter of fact, to make the original equation true would require, more than moving a match, redefining the symbols used.) $\endgroup$– humnCommented Mar 17, 2016 at 21:39
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I think I'm allowed to:
X\III
------ = II
VII
It's hard to tell, but I removed part of an 'X' to make a single piece (placing the spare piece in the division sign), showing an informal "14". 14 divided by 7 equals 2.
shrug "proof"
"XXIII" is 23 and consists of 7 "sticks", where each "X" is two sticks. The division sign is made of 5 sticks (possibly just a coincidence, but "meh"). The "VII" is 7 and consists of 4 "sticks, where each "V" is represented by two sticks.
Remove one stick from the second X in "XXIII" to create "XIIII" (7-1 sticks) and place that stick in the division sign (which now consists of 5+1 sticks).
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$\begingroup$ But you moved two matchsticks! $\endgroup$ Commented Mar 15, 2016 at 19:15
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$\begingroup$ @ABcDexter how? I moved half of the 'X' (which consists of two matches). Unless I copied it wrong, which is possible. $\endgroup$– goodguy5Commented Mar 15, 2016 at 19:17
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$\begingroup$ This was actually my first thought, and the reason I asked the question I did in the comments $\endgroup$ Commented Mar 15, 2016 at 19:20
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1$\begingroup$ Where did the
Iof the 23 go? You placed the spare piece in the division sign right. $\endgroup$ Commented Mar 15, 2016 at 19:21 -
1$\begingroup$ @ABcDexter. (this textblock reads aggressively and that is not what I was going for) Am I typing what I'm trying to say wrong? Can someone please chime in? I'll try one more time to explain what I'm saying: please see the edit. $\endgroup$– goodguy5Commented Mar 15, 2016 at 19:31
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XXIII
----- = II
VII
can be changed to become...
XXIII
----- > II
VII
in which...
I slightly move one of the sticks in the equals sign to become a greater-than sign. Because I cannot visually represent it, the top line will be angled downward to meet its bottom compatriot. Like so, but reversed: ∠
