your common calculations as professionals
It mostly depends on what you're doing. If you're designing a circuit from scratch and need certain voltage out or current out, you're probably going to do Kirchhoff's Voltage Law or Current Law (KVL - KCL). While not too difficult to do (a lot of the time), easy to complicate with larger circuits which require Thevenin / Norton Equivalents. A lot of students find this part of circuit analysis difficult, might be good to look into it a little bit. Otherwise, a large majority of the challenging aspects come in when doing RF and dealing with fields. Gauss's Law and related equations / formulas / theorems are important to understand for such antenna design or other design involving fields.

Edit: Calc and differential equations are used routinely in later EcE courses.