Java-BigDecmial to C#-double, no trailing zeroes

static String customRound(BigDecimal number){
        String numberString = number.setScale(12,BigDecimal.ROUND_HALF_UP).toString();
        int index = 15 - numberString.indexOf('.');
        number = new BigDecimal(numberString)
                .setScale(index,BigDecimal.ROUND_HALF_UP)
                .setScale(12, BigDecimal.ROUND_HALF_UP)
                .stripTrailingZeros();
        double numDouble = Double.parseDouble(number.toString());
        boolean remainder = numDouble % 1 == 0;
        return remainder ? String.format("%.0f", numDouble) : number.toString();
    }