public class Calculator {

	private DoubleMath integerMath;

	public double addition(double firstNumber, double secondNumber) {
		integerMath = (p1, p2) -> p1 + p2;
		return integerMath.operation(firstNumber, secondNumber);
	}

	public double subtraction(double firstNumber, double secondNumber) {
		integerMath = (p1, p2) -> p1 - p2;
		return integerMath.operation(firstNumber, secondNumber);
	}

	public double multiplication(double firstNumber, double secondNumber) {
		integerMath = (p1, p2) -> p1 * p2;
		return integerMath.operation(firstNumber, secondNumber);
	}

	public double divition(double firstNumber, double secondNumber) {
		if (secondNumber == 0) {
			throw new ArithmeticException("divition by zero");
		}
		integerMath = (p1, p2) -> p1 / p2;
		return integerMath.operation(firstNumber, secondNumber);
	}
}