How to learn the common multiples and common factors of primary school mathematics (fifth grade) well?
First, we must master the factors and multiples of a number very skillfully, and then master the common factors and multiples of several numbers through short division. We should use the formula of "edge multiplication, circle multiplication", that is, the common factor should multiply all the divisors on the side by short division, and the common multiple should multiply all the divisors on the circle by short division by quotient. The formula summarized by myself is for reference only.