code: public D multipliedBy(int factor) {
  
          switch (factor) {
              case -1:
                  return this.inverse();
              case 1:
                  return this.self();
              default:
                  return this.with(MathUtils.safeMultiply(this.amount, factor));
          }
  
      }
docs: /*[deutsch]
  <p>Liefert eine Kopie mit dem multiplizierten Betrag. </p>
  
  @param   factor      multiplication factor to be applied
  @return  immutable copy with the multiplied amount
  @throws  ArithmeticException if numeric overflow occurs