return buf.toString();
} else if (number instanceof BigInteger) {
BigInteger bigInt = (BigInteger) number;
boolean isNegative = bigInt.signum() < 0;
if (isNegative) {
bigInt = bigInt.negate();
}
bigInt = bigInt.multiply(BigInteger.valueOf(multiplier));
StringBuilder buf = new StringBuilder();
buf.append(bigInt.toString());
format(isNegative, buf, 0);