BigRational factor = getFactor(i); BigDecimal xToThePower = powerIterator.getCurrentPower(); powerIterator.calculateNextPower(); step = factor.getNumerator().multiply(xToThePower, mathContext).divide(factor.getDenominator(), mathContext); i++; powerIterator.calculateNextPower(); factor = getFactor(i); BigDecimal step2 = factor.getNumerator().multiply(xToThePower, mathContext).divide(factor.getDenominator(), mathContext);