Rubato Foamily onLine

## Application Features

- **Modern Interface Design** - Dark theme, clean and beautiful interface

- **Multiple Calculator Types** - Supports multiple calculation modes including basic, scientific, and unit conversion

- **Complete Calculation History** - Automatically saves calculation records, supports historical viewing and reuse

- **Internationalization Support** - Fully English interface, easy to understand and use

- **High-Performance Computation** - Supports complex mathematical expressions and scientific function calculations

## Main Functions

### 1. Basic Calculator

- **Four Arithmetic Operations**: Addition (+), Subtraction (-), Multiplication (×), Division (÷)

- **Decimal Calculation**: Supports decimal point operations

- **Percentage Calculation**: One-click percentage conversion

- **Position Toggle**: ± buttons quickly change the sign of the value

- **Clear Function**: AC buttons clear all input

### 2. Scientific Calculator

#### Trigonometric Functions

- **Basic Trigonometric Functions**: sin, cos, tan

- **Inverse Trigonometric Functions**: asin, acos, atan

- **Angle Mode Switching**: RAD (radians) / DEG (degrees)

#### Logarithmic and Exponential Functions

- **Common Logarithm**: log (base 10)

- **Natural Logarithm**: ln (base e)

- **Exponential Function**: exp (e raised to the power of x)

- **Power of 10**: 10^x

#### Advanced Mathematical Functions

- **Power Operation**: x^y (arbitrary power)

- **Square Root**: √x

- **Factorion**: n! (supports integers from 0 to 20)

- **Absolute Value**: |x|

- **Floor Down**: ⌊x⌋

- **Floor Up**: ⌈x⌉

- **Random Number**: Rand (random decimal between 0 and 1)

#### Mathematical Constants

- **Pi**: π (3.14159...)

- **Natural constant**: e (2.71828...)

### 3. Unit Converters

#### Length Conversion

- Meter (m), Centimeter (cm), Millimeter (mm), Kilometer (km)

- Inch (in), Foot (ft), Yard (yard), Mile (mile)

#### Weight Conversion

- Gram (g), Kilogram (kg), Ton (t)

- Ounce (oz), Pound (lb)

#### Temperature Conversion

- Celsius (°C), Fahrenheit (°F), Kelvin (K)

#### Area Conversion

- Square meter (m²), Square centimeter (cm²), Square kilometer (km²)

- Square inch (in²), Square foot (ft²), Acre (acre)

#### Volume Conversion

- Cubic meter (m³), Liter (L), Milliliter (mL)

- Gallon (gal), Pint (pt), Fluid Ounce (fl oz)

### 4. Number System Converter

- **Binary**: A number system consisting of 0s and 1s

- **Octal**: A number system consisting of 0s and 7s

- **Decimal**: A standard number system consisting of 0s and 9s

- **Hexadecimal**: A number system consisting of 0s and 9s and A-Fs

### 5. Currency Converter
Supports real-time exchange rate conversion for major international currencies:

- US Dollar (USD), Euro (EUR), British Pound (GBP)

- Chinese Yuan (CNY), Japanese Yen (JPY), Korean Won (KRW)

- Canadian Dollar (CAD), Australian Dollar (AUD), etc.

### 6. Loan Calculator

- **Equal Installment Repayment**: Fixed monthly repayment amount

- **Equal Principal Repayment**: Fixed monthly principal repayment, decreasing interest

- **Interest Calculator**: Automatically calculates total interest and monthly payment

### 7. Investment Calculator

- **Compound Interest Calculator**: Supports different compound interest frequencies

- **Investment Returns:** Calculates the rate of return on investment

**Time Value of Money:** Considers the time value of money