insufficient precision when evaluating calculated item and trigger expressions

The following expression is evaluated incorrectly, yielding "false": 9*(1/9)=1.

The reason it happens is due to expression rewriting in function evaluate(). There 1/9 is evaluated first and the result is inserted into the original expression with 6 digits after the decimal point: 9*0.111111=1. This is further evaluated as 0.999999=1, which is false.