How does the Gopher do it?

[Belwarrior]

I'm sure there is a method of mathematics involved but so far the program have no problems guessing my numbers.

Not sure whether this has been posted here before but guys, have a look at the following link

http://www.learnenglish.org.uk/games/magic-gopher-central.swf

[cjolley]

There are only a few possible final results and they all have the same symbol.
Though, the symbol changes from run to run so it isn't so obvious.

I did a formula on it when a friend emailed me the same question about a year ago.
When I get to work tomorrow I'll see if I can find it.

[the main lobe]

Fun problem

This is an easy one, but only when you take the time to write it down.
Consider the two digits A and B. A is the 10s digit, B is the ones.
So this means the 2 digit number is 10A+B.
Then subtract (A+B).
Now we have 9A.

Notice in the chart that all the multiples of 9 are always the same symbol, and always the right answer.

This was fun, thanks for posting the link.