Java's Bigdecimal.divide and rounding

As specified in javadoc, a BigDecimal is defined by an integer value and a scale.

The value of the number represented by the BigDecimal is therefore (unscaledValue × 10^(-scale)).

So BigDecimal("1761e+5") has scale -5 and BigDecimal(176100000) has scale 0.

The division of the two BigDecimal is done using the -5 and 0 scales respectively because the scales are not specified when dividing. The divide documentation explains why the results are different.

divide

public BigDecimal divide(BigDecimal divisor)

Returns a BigDecimal whose value is (this / divisor), and whose preferred scale is (this.scale() - divisor.scale()); if the exact quotient cannot be represented (because it has a non-terminating decimal expansion) an ArithmeticException is thrown.

Parameters:

divisor - value by which this BigDecimal is to be divided.

Returns:

this / divisor

Throws:

ArithmeticException — if the exact quotient does not have a terminating decimal expansion

Since:

1.5

If you specify a scale when dividing, e.g. dividendo.divide(BigDecimal.valueOf(1000), 0, RoundingMode.HALF_UP) you will get the same result.

The expressions new BigDecimal("176100000") and new BigDecimal("1761e+5") are not equal. BigDecimal keeps track of both value, and precision.

BigDecimal("176100000") has 9 digits of precision and is represented internally as the BigInteger("176100000"), multiplied by 1. BigDecimal("1761e+5") has 4 digits of precision and is represented internally as the BigInteger("1761"), multiplied by 100000.

When you a divide a BigDecimal by a value, the result respects the digits of precision, resulting in different outputs for seemingly equal values.

for your division with BigDecimal.

dividendo.divide(divisor,2,RoundingMode.CEILING)//00.00 nothing for up and nothing for down

in this operation have a precision for two decimals.