1.最大公约数辗转相除法
int t;
while(b!=0){
t=a%b;
a=b;
b=t;

}

printf("the gcd is %d\n",a);

2.最小公倍数
最小公倍数乘以最大公约数等于两数乘积，所以最小公倍数等于两数乘积除以最大公约数。

include<stdio.h>

include<math.h>

int main(void){

printf("please input two number:");
int a=0,b=0;
scanf("%d %d",&a,&b);
int  temp1=a,temp2=b;
int t;
while(b!=0){
    t=a%b;
    a=b;
    b=t;

}

printf("the gcd is %d\n",a);

int zxg=temp1*temp2/a;
printf("the zxgbs is %d\n",zxg);

}