C++. Абстрактный класс.

[Александр222]

Задача.
image_2020-10-15_141330.jpg

Посмотрите, пожалуйста, код. Есть ли здесь хоть что-то правильное? На данном этапе имеется 2 ошибки в Subtraction и Multiplication, связанные с other (две последние реализации).
Pair.h

class Pair{

public:
    long int NumberFirst;
    unsigned short int NumberSecond;

    virtual void display() = 0;
    virtual double getDouble();

    virtual void Addition(const Pair& other);
    virtual void Subtraction(const Pair& other);
    virtual void Multiplication(const Pair& other);
};

class Fraction: public Pair{
public:  
  
    Fraction();
    Fraction(long int _fNumberFirst, unsigned short int _fNumberSecond);

    void Addition(const Pair& other);
    void Subtraction(const Pair& other);
    void Multiplication(const Pair& other);

    void Comparison(Fraction first, Fraction second);
    void display();
    void getObject(double a);
    double getDouble();    
};

Pair.cpp

#include "Pair.h"
#include <cmath>
#include <iostream>

double Pair::getDouble(){ return 0.0; }

void Pair::Addition(const Pair& other){}
void Pair::Subtraction(const Pair& other){}
void Pair::Multiplication(const Pair& other){}

Fraction::Fraction() {
    NumberFirst = 0;
    NumberSecond = 0;
}
Fraction::Fraction(long int _fNumberFirst, unsigned short int _fNumberSecond) {
    NumberFirst = _fNumberFirst;
    NumberSecond = _fNumberSecond;
}
void Fraction::Addition(const Pair& other) {
    Fraction TEMP;
    TEMP.NumberFirst = (*this).NumberFirst + other.NumberFirst;
    TEMP.NumberSecond = (*this).NumberSecond + other.NumberSecond;
    if (TEMP.NumberSecond >= 100) {
        TEMP.NumberSecond -= 100;
        TEMP.NumberFirst++;
    }
    return;
}

void Fraction::display() {
    std::cout << NumberFirst << "." << NumberSecond << std::endl;
}
void Fraction::getObject(double a) {
    if (static_cast<int>(a / 0.0001) % 10 != 0) {
        NumberSecond = static_cast<int>(abs(a * 10000)) % 10000;
    }
    else if (static_cast<int>(a / 0.001) % 10 != 0) {
        NumberSecond = static_cast<int>(abs(a * 1000)) % 1000;

    }
    else if (static_cast<int>(a / 0.01) % 10 != 0) {
        NumberSecond = static_cast<int>(abs(a * 100)) % 100;
    }
    else if (static_cast<int>(a / 0.1) % 10 != 0) {
        NumberSecond = static_cast<int>(abs(a * 10)) % 10;
    }
    else if (static_cast<int>(a / 1) % 10 != 0) {
        NumberSecond = static_cast<int>(abs(a));
    }
    NumberFirst = static_cast<long int>(a);
}

double Fraction::getDouble(){
    double var{ 0 };
    var += this->NumberFirst;
    if (NumberSecond / 100000 != 0) {
        if (NumberFirst > 0) var += static_cast<int>(NumberSecond) * 0.000001;
        else var -= static_cast<int>(NumberSecond) * 0.000001;
    }
    else if (NumberSecond / 10000 != 0) {
        if (NumberFirst > 0) var += static_cast<int>(NumberSecond) * 0.00001;
        else var -= static_cast<int>(NumberSecond) * 0.00001;
    }
    else if (NumberSecond / 1000 != 0) {
        if (NumberFirst > 0) var += static_cast<int>(NumberSecond) * 0.0001;
        else var -= static_cast<int>(NumberSecond) * 0.0001;
    }
    else if (NumberSecond / 100 != 0) {
        if (NumberFirst > 0) var += static_cast<int>(NumberSecond) * 0.001;
        else var -= static_cast<int>(NumberSecond) * 0.001;
    }
    else if (NumberSecond / 10 != 0) {
        if (NumberFirst > 0) var += static_cast<int>(NumberSecond) * 0.01;
        else var -= static_cast<int>(NumberSecond) * 0.01;
    }
    else if (NumberSecond != 0) {
        if (NumberFirst > 0) var += static_cast<int>(NumberSecond) * 0.1;
        else var -= static_cast<int>(NumberSecond) * 0.1;
    }

    return var;
}

void Fraction::Subtraction(const Pair& other) {
    Fraction TEMP;
    double var;
    var = (*this).getDouble() - other.getDouble();
    TEMP.getObject(var);
}
void Fraction::Multiplication(const Pair& other) {
    Fraction TEMP;
    double i;
    i = (*this).getDouble() * other.getDouble();
    TEMP.getObject(i);
}

void Fraction::Comparison(Fraction first, Fraction second){
    if (first.NumberFirst == NumberFirst && second.NumberSecond == NumberSecond) std::cout << "The numbers are equal." << std::endl;
    else    {
        if ((first.NumberFirst - second.NumberSecond) > 0) std::cout << "The number first is greater than the number second." << std::endl;
        else std::cout << "The number first is less than the number second." << std::endl;
    }
}