This program will calculate factorials, permutations and combinations. For this assignment the following methods must be coded:

A data validation method which accepts a whole number between the values of $0$ and $12$

A method that calculates the factorial of a number: $nn**(n-1)**dots**1,01$ and $11$

A method that calculates the combination of $r$ things taken from $n$ objects without repetition where order matters $nr$

${?}_n{C}_r=\frac{n!}{(r!)(n-r)!}$

A method that calculates the permutation of $r$ items from $n$ objects without repetition where order doesn't matter $nr$

${?}_n{P}_r=\frac{n!}{n-r}!$