{"0_", 0, false, nil, 10, 1, errInvalSep, 0},
	{"0__0", 0, false, nil, 8, 1, errInvalSep, 0},
	{"0x___0", 0, false, nil, 16, 1, errInvalSep, 0},
	{"0_x", 0, false, nil, 10, 1, errInvalSep, 'x'},
	{"0_8", 0, false, nil, 10, 1, errInvalSep, '8'},
	{"123_.", 0, true, nat{123}, 10, 0, errInvalSep, 0},
	{"._123", 0, true, nat{123}, 10, -3, errInvalSep, 0},
	{"0b__1000", 0, false, nat{0x8}, 2, 4, errInvalSep, 0},

		// underscores
		{"0_0", 0},
		{"1_000.", 1000},
		{"1_2_3.4_5_6", 123.456},
		{"1.0e0_0", 1},
		{"1p+1_0", 1024},
		{"0b_1000", 0x8},
		{"0b_1011_1101", 0xbd},
		{"0x_f0_0d_1eP+0_8", 0xf00d1e00},
	} {
		var x Float
		x.SetPrec(53)
		_, ok := x.SetString(test.s)
		if math.IsNaN(test.x) {
			// test.s is invalid
			if ok {
				t.Errorf("%s: want parse error", test.s)
			}