public String toPlainString() {
        return PLAIN_FORMAT.format(this).toString();
    }
@Test
    public void testToPlainString() {
        assertEquals("0.0015", Fiat.valueOf("EUR", 15).toPlainString());
        assertEquals("1.23", parseFiat("EUR", "1.23").toPlainString());

        assertEquals("0.1", parseFiat("EUR", "0.1").toPlainString());
        assertEquals("1.1", parseFiat("EUR", "1.1").toPlainString());
        assertEquals("21.12", parseFiat("EUR", "21.12").toPlainString());
        assertEquals("321.123", parseFiat("EUR", "321.123").toPlainString());
        assertEquals("4321.1234", parseFiat("EUR", "4321.1234").toPlainString());

        // check there are no trailing zeros
        assertEquals("1", parseFiat("EUR", "1.0").toPlainString());
        assertEquals("2", parseFiat("EUR", "2.00").toPlainString());
        assertEquals("3", parseFiat("EUR", "3.000").toPlainString());
        assertEquals("4", parseFiat("EUR", "4.0000").toPlainString());
    }