Properties of (1) greatest common factor: [1]: The quotient obtained by dividing two numbers by their greatest common factor is coprime. [2]: The factor of the greatest common factor of two numbers is the factor of these two numbers. (2) The nature of the least common multiple: [1]: Any common multiple of two numbers is a multiple of their least common multiple. [2]: The product of the least common multiple and the greatest common factor of two numbers is equal to the product of these two numbers. (Excerpted from A Dictionary of Mathematics for Primary School Students).