The numbers and symbols below are placed onto five vertical strips of paper:
= = 8 8 2
+ - 2 6 1
= = 5 2 0
+ + 9 1 9
Rotate and rearrange the strips so that four valid equations appear across the rows.
For example, if you had the 2×1 strips:
= = 6 6 8
- + 1 1 5
You could rearrange them as:
5 + 1 = 6
8 = 9 - 1
Note: Consider the numbers as they appear on a digital watch; 0, 1, 2, 5 and 8 are the same when rotated 180°, while 6 and 9 rotate to each other.
(In case there's a problem with the link in the previous comment...)
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8 = 6 + 2
6 - 5 = 1
2 = 2 + 0
1 + 8 = 9
If it isn't clear these represent the ordering of the columns:
4th - rightside up
2nd - rightside up
3rd - upside down
1st - upside down
5th - rightside up
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Since there (should/can) be only one equal sign in any given row, one of the two first columns must be flipped, and they must be the 2nd and 4th column.
So, we have the remaining strips which can be placed in only the 1st, 3rd, and 5th positions.
It doesn't leave too many combinations (there's only one 1 on the end... so we need an 8, 1, 9 relation and a 2, 6, 8 relation... and they both use a +... so, there are not many possibilities to sort through.
full solution
