// dfmt off
T lread(T=long)(){return readln.chomp.to!T;}T[] lreads(T=long)(long n){return iota(n).map!((_)=>lread!T).array;}
T[] aryread(T=long)(){return readln.split.to!(T[]);}void arywrite(T)(T a){a.map!text.join(' ').writeln;}
void scan(L...)(ref L A){auto l=readln.split;foreach(i,T;L){A[i]=l[i].to!T;}}alias sread=()=>readln.chomp();
void dprint(L...)(lazy L A){debug{auto l=new string[](L.length);static foreach(i,a;A)l[i]=a.text;arywrite(l);}}
static immutable MOD=10^^9+7;alias PQueue(T,alias l="b<a")=BinaryHeap!(Array!T,l);import std, core.bitop;
// dfmt on

void main()
{
    long T = lread();
    foreach (i; 0 .. T)
    {
        long N, M, A, B;
        scan(N, M, A, B);
        floor_sum(N, M, A, B).writeln();
    }
}

long floor_sum(long n, long m, long a, long b)
{
    long ans;
    if (m <= a)
    {
        ans += (n - 1) * n * (a / m) / 2;
        a %= m;
    }
    if (m <= b)
    {
        ans += n * (b / m);
        b %= m;
    }
    long y_max = (a * n + b) / m, x_max = (y_max * m - b);
    if (y_max == 0)
        return ans;
    ans += (n - (x_max + a - 1) / a) * y_max;
    ans += floor_sum(y_max, a, m, (a - x_max % a) % a);
    return ans;
}
