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     -------  =  II  

All you need to do is move one matchstick from the roman numerals to make the equation true.

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move or remove? – question_asker Mar 15 at 18:55
@question_asker move... – ABcDexter Mar 15 at 18:56
up vote 7 down vote accepted

You could move...

The last I from the numerator onto the top of the result, like so:

---- = $\pi$
It's an approximation, but yesterday was Pi Day.

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@ttt it will always be yesterday relative to the posting of the question – question_asker Mar 15 at 20:05
@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...) – TTT Mar 15 at 20:09
@ttt but the question isn't posted six months from now, it was posted today – question_asker Mar 15 at 20:18
@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. – jpmc26 Mar 15 at 23:07
@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. – question_asker Mar 16 at 14:56

If in “make the equation true” only the words make and true are taken literally:

——   ≠   II

As quintopia points out, this is no longer an equation. (A deserved custard $\pi$ in my face.)

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Well, that would go into the lateral-thinking part ;-) – ABcDexter Mar 15 at 19:15
Hahahahahaha. Well played! – Khale_Kitha Mar 15 at 22:46
Is an inequality considered a equation? – quintopia Mar 17 at 17:53
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.) – humn Mar 17 at 21:39

I think I'm allowed to:

------ = II
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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But you moved two matchsticks! – ABcDexter Mar 15 at 19:15
@ABcDexter how? I moved half of the 'X' (which consists of two matches). Unless I copied it wrong, which is possible. – goodguy5 Mar 15 at 19:17
This was actually my first thought, and the reason I asked the question I did in the comments – question_asker Mar 15 at 19:20
Where did the I of the 23 go? You placed the spare piece in the division sign right. – ABcDexter Mar 15 at 19:21
@ABcDexter yes. the "spare" piece is in the division sign (which is composed of several "sticks" in your example). That leaves an 'X' and four 'I's, though, one of them is a bit crooked. – goodguy5 Mar 15 at 19:23

----- = II

can be changed to become...

----- > II

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: ∠

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