I decided to make this thing where you can put in numbers and it'll find an expression using those numbers to make another number. I haven't really though of a catchy name for this :(. This was originally designed for a game played on Sydney public transport where the digits of the ID code at the front of the carriage/bus is used to make the number 10. It also works well for the four fours puzzle, and the numbers round of Letters and Numbers (or Countdown in the UK). On my machine with default settings it manages to process four and fewer numbers almost instantaneously. For five numbers it usually takes a couple of seconds, and for six you'll be in for a good wait. Depending on the settings, it may also be able to guarantee that no solution is possible given the operations it's allowed to perform. NEW: I've implemented most of the features that I could think of, but I've still got a few small ideas left. If you've got any suggestions I'd be glad to here them.
I was and still am quite surprised at the what IMO is the nonintuitively high chance for target to be reached using say 4 or 5 numbers, especially for somewhat larger targets. I find there's a certain delight when it spits out an interesting/convoluted solution which manages to reach a difficult goal.