Scientific Calculator (previously known as PowerCalc) is an excellent scientific calculator app for Android. It retains the simplicity and familiarity of RealCalc's UI while having lots more calculation buttons. The equation editor can handle brackets nicely, the display is multi-line showing both the equation and its result and there is even history. If you use a scientific calculator every day, then I recommend this over the simpler RealCalc.
Tried with: PowerCalc 1.6.2, Android 5.0.2 (Lollipop) and Moto G 2nd Gen (XT1068)