Number Dumber is a digit arithmetic puzzle, in which one has 4 digits, and the 4 standard math operators +/-/*/// (last one is division), and a final number to make.
One has to make the final number using the 4 digits, using these 4 math ops. No brackets (grouping) allowed, and expressions are evaluated from left to right, as in
7 - 3 * 5 / 1 is evaluated as, 4 * 5 / 1 20 / 1 20
Notice that using 4 4's with math operators to generate numbers from 1 to 100, is kind of like a special application of this.
I have written a solver, that solves the NumberDumber, given the digits and the final number. The solver, as well as the puzzle creator are here. Get some puzzles and try solving them, by not using solver.
The puzzles are reasonably tough (how tough can be digit arithmetic :-)), as in they have a unique solution only.