AcclaimSublevel19 This is in fact standard calculator behaviour!
Standard does not mean right :-) Even worse, this is counter intuitive for the "normies" (ie: non technical people). Ask any normie to tell you how much is 25 + 50% and I bet no one will ever think about adding 150% because people don't think that way (bad school systems, etc. but that's not the point).
There are also a lot of apps which do not pay attention to math priorities and happily tell you that 5+6x2 = 13 !!!
I absolutely love the calculator I recommended and use because it takes care of all these rules and provide an accurate result in all cases I tested.