MathUtils { public static BigDecimal invert(BigDecimal d) { return divide(BigDecimal.ONE, d); }  static BigDecimal divide(BigDecimal dividend, BigDecimal divisor); static BigDecimal invert(BigDecimal d); static double percentChange(BigDecimal oldValue, BigDecimal newValue); static boolean equalsByComparingTo(BigDecimal bd1, BigDecimal bd2);  }
@Test public void testInvert() { assertThat(MathUtils.invert(new BigDecimal("2.3"))).isEqualByComparingTo("0.4347826087"); }