Solving Combinatorics vs What Numbers:number theory Usage & Stats
Finally there is the app that provides all 6 variations of combinatorics with step by step solutions:
- permutation without repetition: Arranging elements without repetition.
- permutation with repetition: Arranging elements with repetition.
- combination without repetition: Selecting elements without considering the order.
- combination with repetition: Selecting elements with consideration of the order.
- variation without repetition: Arranging elements with fixed length without repetition.
- variation with repetition: Arranging elements with fixed length with repetition.
You only have to enter your values k and n. The values must be entered as natural numbers. The only exception is the k value for permutation with repitition. This requires several k values, which must be entered separated by semicolons.
All calculations are stored in the history. The final solution can be shared.
[ Contents ]
- all 6 variations of combinatorics
- results are calculated and shown in detail
- history to save the input
- detailed solution
- natural numbers are supported
- option to remove advertisements
[ Usage ]
- there are fields for entering values using a special keyboard
- multiple k values can be entered using the semicolon key
- press the check mark button at the bottom right to start the calculation
- if values are missing, the corresponding field is highlighted in yellow
- if the values are incorrect, the affected field will be highlighted in red
- a short message explains why a value is incorrect
- the entries in the history can be deleted or sorted
- if you select an entry in the history, it will be automatically loaded for the calculation
- the whole history can be deleted by pressing a button
- solutions can be shared
- Apple App Store
- Free
- Education
Store Rank
- -
With this application, you can quickly find out what number the number corresponds to. For example, if you search for "7", the app will tell you if the number is a prime number, a palindrome number, a happy number, a harshad number, etc.
・Corresponding Number Theory
Prime number
Fibonacci number
Palindrome number
Armstrong number
Happy number
Sad number
Circular Prime Number
Perfect Square
Perfect Cube
Harshad Number
Duck Number
Spy Number
Automorphic number
Strobogrammatic Number
Disarium Number
Emirp Number
・Functions
1. when you enter a number, you can immediately determine what the number theory is.
2. displays a modal with the meaning of the number theory and an example when tapped.
・Displays a modal with the meaning of the number theory and an example when tapped.
===
1. Prime number
2. A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself.
3. Example: 2,3,5,7...
===
1. Harshad Number
2. A Harshad number is a number that is divisible by the sum of its digits.
3. Example: 18...
===
1. Armstrong number
2. An Armstrong number is a number that is equal to the sum of cubes of its digits.
3. Example: 153,370,371,407...
===
1. Palindrome number
2. A palindrome number is a number that is the same when read forwards or backwards.
3. Example: 121,12321...
===
1. Automorphic number
2. An automorphic number is a number whose square "ends" in the same digits as the number itself.
3. Example: 5, 6, 25, 76, 376, 625
===
1. Emirp Number
2. An emirp number is a prime number that results in a different prime when its digits are reverse.
3. Example: 13, 17, 31, 37...
- Apple App Store
- Free
- Reference
Store Rank
- -
Solving Combinatorics VS. 
What Numbers:number theoryJanuary 13, 2026