The drl test case below illustrates a problem with math inside of drools when using the mvel dialect. When using autoboxing the order of operations (and parens) are not respected. This is using drools 5.0M1 and mvel-2.0-dp4.jar. The correct answer is 80 and the answer provided with autoboxing in the mvel dialect is 100. I'm uncertain of how to create a viable test case in pure mvel to add it to their jira. Any help is appreciated, Thanks, Joe package test; dialect "mvel" rule "TestRule" when then double value=(2*new Double("50"))-10-10; System.out.println(value); double valueTwo=(2*50)-10-10; System.out.println(valueTwo); End RESULTS Wrong = 100.0 Right = 80.0