(my officemate received the following via e-mail; thought I'd post it here
in case anyone is interested)


Make each equation equal to 10 using the following symbols:
+, -, x, /, ., ^, sqrt, and ( ).  The digits MUST be kept in the
order given, and each number can only be used once.  Good luck!


a) 12 = 10
b) 123 = 10
c) 1234 = 10
d) 12345 = 10
e) 123456 = 10
f) 1234567 = 10
g) 12345678 = 10
h) 123456789 = 10

17 responses total.

(linked to games)

a) sqrt(.1^(-2)) = 10

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c can also be done with just +.  1+2+3+4.  I'm not sure there's any
other solution using just one character in such a simple pattern.

d) 12-3-4+5 = 10

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123-45-67+8-9

So except for (a) and (b), they can all be done using only + and -.

It becomes a more challenging problem if we define a solution as
"better" if it uses more of the specified symbols.  By this measure,
#4 is the best solution so far, since it uses five of them: sqrt, .,
-, *, and ^.

(I'm not counting multiple uses of the same symbol.  Nor am I
counting parentheses, since they're essentially "free".)

So, how 'bout some better solutions?

I don't know about this making up 'rules' about what is 'better'as you
go...... #11 was the first one using a three digit number. Try doing it
using a four digit number.  Also, I think it is 'better' using the *least*
number of symbols: the Thoreau principle. By this test, #6 is best. Your
criterion is the IRS principle.

Whatever. I'm just suggesting a way to make the puzzle more
challenging. In the future, I'll be sure to use my powers of
prescience and make any suggestions for improvement at least
a week before a puzzle is posted.

i'm not sure if this solution is valid, but i thought i'd suggest it anyways:
1^2=1^0

That's the solution to *some* math puzzle - but which one?

ar. that's a, but i just looked up and realized that the rval has to be 10...

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