}
	// test other ranges
	for i, r := range mulRangesZ {
		prod := tmp.MulRange(r.a, r.b).String()
		if prod != r.prod {
			t.Errorf("#%db: got %s; want %s", i, prod, r.prod)
		}
	}
}

func TestBinomial(t *testing.T) {
	var z Int
	for _, test := range []struct {
		n, k int64
		want string
	}{
		{0, 0, "1"},
		{0, 1, "0"},
		{1, 0, "1"},
		{1, 1, "1"},
		{1, 10, "0"},
		{4, 0, "1"},