- Prime Number
- A prime number is a positive ingeger not divisible (without a remainder) by any positive integer other than itself and 1.
- A positive integer can be written uniquely (up to reordering) as a product of prime numbers.
- Example
- 60 = 2 x 2 x 3 x 5 = 2^2 x 3 x 5.
- Coprime
- Two integers a and b are said to be coprime if the only positive integer that evenly divides both of them is 1. That is, the only common positive factor of the two numbers is 1.
- For example, gcd(14,15) = 1 are coprime but gcd(14,21) = 7 are not coprime.