Two methods to find the greatest common divisor in primary school study;

1, respectively decompose the prime factor of each number, and then compare the prime factors of * * * *;

2. Write a short division formula with short division. The reason is similar to the first method, except that the process of finding the common factor and the division process are merged.

It is difficult to input short division by computer. Here, the first method is used to demonstrate two problems:

1 and 12 can be decomposed into 2 * 2 * 3; 32 can be decomposed into 2*2*2*2*2, and it is observed that the male part is 2*2. So the greatest common factor of (12,32) is 4.

2. 135 can be decomposed into 5 * 3 * 3 * 3; 25 can be decomposed into 5*5, and it is observed that the common part is 5. So the greatest common factor of (135,25) is 5.