Any two successive numbers/ integers are always co-prime: Take any consecutive numbers such as 2, 3, or 3, 4 or 5, 6, and so on; they have 1 as their HCF.
Any two consecutive integers are always coprime. Sum of any two coprime numbers is always coprime to their product. 1 is trivially coprime with all numbers. if out of two numbers, any one number is a prime number while the other number is not a multiple of first one, then both are coprime
