CountDown Numbers Game Solver

The app will look for a solution to the CountDown Numbers Game.

The app requests the user to enter a target number and six ‘input numbers’. It will then try to achieve that target value by combining the input numbers, using addition, subtraction, multiplication, division and brackets.
The solution does not have to contain all the input numbers and it can’t use any of the input numbers more than once. The input numbers don’t all have to be different.

If an input is left blank, then it is assumed to be zero.

Suppose we had a target of 241 and we have input numbers:
{ 10, 5, 5, 2, 3, 6 }
then we could find a solution:
241 = ( 10 x 5 x 5 ) - (3 + 6)
Note how both 5's are used, but the 2 is not used at all.

The target and input numbers must be integers and at no intermediate point in the solution provided will there be non-integers. For example (5 / 2 ) x 6 would not be allowed, since (5 / 2) is not an integer.
But ( 5 x 6 ) / 2 is allowed.

This app was produced by Philip Kinlen.
The app is non-commercial. It was developed for fun and is distributed for free.

If you'd like to see the source code, then please go to the following URL in github:
https://github.com/pkinlen/countdownnumbers