String a = "3736186567876876578956958765675671119238118911893939591735";
int aScale = 15;
String b = "748766876876723342238476237823787879183470";
int bScale = 70;
int precision = 21;
RoundingMode rm = RoundingMode.FLOOR;
MathContext mc = new MathContext(precision, rm);
String c = "4.98978611802562512995E+70";
int resScale = -50;
BigDecimal aNumber = new BigDecimal(new BigInteger(a), aScale);
BigDecimal bNumber = new BigDecimal(new BigInteger(b), bScale);