public static String roundStr(double v, int scale) {
		return round(v, scale).toPlainString();
	}
@Test
	public void roundStrTest() {
		final String roundStr = NumberUtil.roundStr(2.647, 2);
		assertEquals(roundStr, "2.65");

		final String roundStr1 = NumberUtil.roundStr(0, 10);
		assertEquals(roundStr1, "0.0000000000");
	}