Rounding necessary with BigDecimal numbers

Question

I want to set scale of two BigDecimal numbers a and b . as in this example :

BigDecimal a = new BigDecimal(\"2.6E-1095\");
        BigD         


        

Answer 1

Rounding is necessary.

In javadoc for BigDecimal, it says BigDecimal is represented as (unscaledValue × 10^-scale), where unscaledValue is an arbitatrily long integer and scale is a 32-bit integer.

2.6*10^-1095 requires a scale of at least 1096 to represent accurately. It can not be represented accurately with (any integer)*10^-113. Therefore, you need to providing a roundingMode.