[masida]

Python does it:

  >>> from decimal import Decimal
  >>> Decimal(0.1)
  Decimal('0.1000000000000000055511151231257827021181583404541015625')
  >>> Decimal(1e50)
  Decimal('100000000000000007629769841091887003294964970946560')

[haberman]

Great to know, thanks!