Maths problem

[Gordon100]

How can I arrive at a figure of -10 (minus 10) having used all numbers between 1 and 9 but only adding or subtracting?

[kempie]

Can you combine the digits e.g. 19, 47, etc. or must they be treated as single digits?

[Gordon100]

As far as I know they need to be treated as single digits.
It seems to my simple brain that there is always going to be a problem with the odd numbers!

[Dinkypuzzled]

Would this be allowed?

8 to the power of two minus 4 to the power of 3, -5 -6 -7 -1 +9.

[Dinkypuzzled]

or -

49-58-3-7+2+6+1

[Gnu]

The numbers 1 to 9 add up to 45, if my maths is right. To have some added, then some taken away to get -10 would mean that the added ones would total 17.5, and the subtracted ones total 27.5.

These add up to 45 and when one is subtracted from the other it leaves -10.

As all the numbers are whole numbers, you can't get these totals.

Your argument about odd numbers is also good, as when you add or subtract two of them you get an even number, same with four of them. In this problem you've got 5 so the result will always be an odd number and not -10.

[Gordon100]

Thanks for your help.
I think Dinkypzzled`s second answer is the one I`ll go for.
I`ll let you know next week!