Combinatorics Mathematics is a free Android app developed by Pieter Pareit that helps in calculating and enumerating all possible permutations, combinations, and more. The app is designed for students, teachers, and professionals who need an easy-to-use calculator for their mathematical problems.

The app has several algorithms, including permutations of letters, anagrams of words, k-permutations of letters, combinations of letters, and combinations with repetitions of letters. It displays the number of permutations, combinations, and other mathematical symbols with well-formatted tex/latex. Additionally, the app allows users to share their calculation results through email or save them to a file.

The app's interface is user-friendly and straightforward, making it easy for anyone to use. It also has an option to send feedback from within the application. Overall, Combinatorics Mathematics is an excellent tool for anyone who needs to calculate and enumerate mathematical problems involving permutations and combinations.