Given a number x, Find y (y > 0) such that x*y + 1 is not a prime.
Input : 2 Output : 4 Input : 5 Output : 3
x*(x-2) + 1 = (x-1)^2 which is not a prime.
For x > 2, y will be x-2 otherwise y will be x+2
GeeksforGeeks has prepared a complete interview preparation course with premium videos, theory, practice problems, TA support and many more features. Please refer Placement 100 for details
- Find coordinates of a prime number in a Prime Spiral
- Find the minimum number to be added to N to make it a prime number
- Program to find the Nth Prime Number
- Program to find the next prime number
- Find the position of the given Prime Number
- Find all the prime numbers of given number of digits
- Find largest prime factor of a number
- Find sum of a number and its maximum prime factor
- Find prime number K in an array such that (A[i] % K) is maximum
- Analysis of Different Methods to find Prime Number in Python
- Find the number of primitive roots modulo prime
- Find Largest Special Prime which is less than or equal to a given number
- Find a sequence of N prime numbers whose sum is a composite number
- Find third number such that sum of all three number becomes prime
- Quick ways to check for Prime and find next Prime in Java
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to email@example.com. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.