I do believe you may be correct, but it still isn't semantically correct.
Hmmm...
I don't have access to an Arduino to test, but perhaps this line:
lcd.print (voltValue*c)*(mvoltValue*d)/e;
is equivalent to multiplying the return value from lcd.print() by something, and ignoring the result:
((mvoltValue*d)/e)*lcd.print (voltValue*c);