You can enjoy mental arithmetic.
Kind of calculation are the following.
Arithmetic
- Addition: Calculate addition
- Subtraction: Calculate subtraction
- Multiplication: Calculate multiplication
- Division: Calculate division
Number
- Remainder: Calculate remainder
- GCD: Calculate Greatest Common Divisor
- LCM: Calculate Least Common Multiple
Rational Number
- Fraction: Find a decimal number equals to given fraction
- Decimal: Find a fraction equals to given decimal number