Calculator

1. Multifunction - a calculator supporting nested brackets, power, root, Pi, add, subtract, multiply and divide;
2. Intuition - a calculator where the entire inputed expression is shown on the screen;
3. Powerful - a calculator that can calculate power to float value. For example, 8^(1÷3) calculates the cube root of 8;
4. Friendly - a calculator where the result is formatted as exponent for large number.