又见GCD

2
6 2
12 4

4
8

#include <stdio.h>

int gcd(int a, int b){
    return b ? gcd(b, a % b) : a;
}

int main()
{
    int n, a, b, c;
    scanf("%d", &n);
    while(n--){
        scanf("%d%d", &a, &b);
        for(c = b << 1; ; c += b){
            if(gcd(a, c) == b) break;
        }
        printf("%d\n", c);
    }
    return 0;
}