if the operands-logic is set to "random" and the number of operands in ECC+ ist set to "3", there will always be only the same operators, e.g. 5 + 4 + 8 or 8 - 5 - 2, but no mixes like 8 + 6 - 4.
Seems to be a bug. I use the current version of ECC+ on Joomla 2.5.4. Numbers are restricted to 59, and numbers are expressed also as words.