Factorial puzzles

You can give students either of these puzzles after learning about factorials, but not both, as once the method has been discovered for solving one puzzle, the other puzzle becomes trivial. Further, it's best not to give these puzzles immediately after an introduction to factorials, as looking for occurences of the factorial symbol is pretty much a dead give-away.


Make the equation true by adding or removing one dot:

Solution


Make the equation true by removing three dots:

Solution