Put in a mathematical expression (no variables) and watch it evaluate it! Try out 40 - (20 * (1-5)-10) which should equal 130 Notice how it is flexible with spacing Note: it doesn't support negative numbers alone (just because the negative and minus sign are the same thing) so if you want to use a negative number, say -100, type in (0-100)
The algorithm I used for this was a modified version of the Shunting-yard algorithm https://en.wikipedia.org/wiki/Shunting-yard_algorithm https://www.geeksforgeeks.org/expression-evaluation/
