Sounds good. For the final precision calc we will use the maxlength and scale for the BigDecimal columnExp. That means we will consider all the data having this precision and scale.  As the others type in the mentioned algo, it will come this way
if precision is 32 and scale is 4 for column, for 2 BigDecimal data of this type, the result precision will come 33 and scale 4, (and it increments this way)..  Is this correct?  I doubt abt the usage of this now..  What do u say?  Am I missing any thing?