I have some matchsticks set up like this: I + XI = X. If you do not know Roman numerals, here is a quick starter: I=1 II=2 III=3 IV=4 V=5 VI=6 VII=7 VIII=8 IX=9 X=10 XI=11 XII=12 XIII=13 XIV=14 XV=15...... Of course, I + XI = X is wrong. You are told to move the minimum number of matchsticks to make the question correct. So, how many do you have to move?
Most people would get to one move at the least, but the real answer is zero moves. If you rotate the whole question around 180 degrees, it will display this: X = IX + I