Number Series Inheritance ISC 2018

A superclass Number is defined to calculate the factorial of a number. Define a subclass Series to find the sum of the series S = 1! + 2! + 3! + 4! + … + n!

The details of the members of both the classes are given below:

Class name: Number
Data members/instance variables:
n: to store an integer number.
Member functions/methods:
Number(int num): parameterized constructor to initialize the data member n = num.
int factorial(int a): returns the factorial of a number (factorial of n = 1 × 2 × 3 × … × n).
void display(): displays the data member

Class name: Series
Data members/instance variables:
sum: to store the sum of the series.
Member functions/methods:
Series(…): parameterized constructor to initialize the data members of both the classes.
void calSum(): calculates the sum of the given series.
void display(): displays the data members of both the classes.

Assume that the superclass Number has been defined. Using the concept of inheritance, specify the class Series giving details of the constructor, void calSum() and void display().

The superclass, main function and algorithm need not be written.

class Series extends Number{
    int sum;
    public Series(int num){
        super(num);
        sum = 0;
    }
    public void calSum(){
        for(int i = 1; i <= n; i++)
            sum += factorial(i);
    }
    public void display(){
        super.display();
        System.out.println("Sum = " + sum);
    }
}

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