Question 1

#include <iostream>
using namespace std;
int main ()
{
        int i, n;
        cout << "n = ";
        cin >> n;
        i = 1;
        while (i <= n)
        {
                cout << i << " ";
                i = i + 1;              // i++;
        }
        return 0;
}

Question 2

#include <iostream>
using namespace std;
int main ()
{
    int mark;
    do {
        cout << "Enter the mark = ";
        cin >> mark;
        if( mark < 0 || mark > 100)
            cout << "Invalid input, please re-enter" << endl;
    } while ((mark < 0) || (mark > 100));
    cout << "The mark you have entered is " << mark;
    return 0;
}

Question 3

#include <iostream>
using namespace std;
int main ()
{
     int number, count=0, sum=0;
     int c;                     // Boolean variable
     do {
           count = count + 1;
           cout << "Number " << count << " = ";
           cin >> number;
           sum = sum + number;
           cout << "Continue (yes=1/no=0)? ";
           cin >> c;
           cout << endl;
      } while (c == 1);
      cout << "Sum = " << sum << endl;
    return 0;
}

Question 4

#include <iostream>
#include <tgmath.h>
using namespace std;
int main ()
{
     float a, b, c, delta, root1, root2;
     int cont;          // Boolean variable
     do {
          cout << "Solving quadratic equation: ax^2+bx+c=0" << endl;
          do {
                  cout << "a = ";
                  cin >> a;
                  if (a == 0)
                        cout << "a can't be equal to 0" << endl;
          } while (a == 0);
          cout << "b = ";
          cin >> b;
          cout << "c = ";
          cin >> c;
          delta = b * b - 4 * a * c;
          if (delta > 0)
          {
               root1 = (-b + sqrt(delta)) / (2 * a);
               root2 = (-b - sqrt(delta)) / (2 * a);
               cout << "There are two real roots" << endl;
               cout << "They are " << root1 << " and "<< root2 << endl;
          }
          else if (delta == 0)
          {
               root1 = -b / (2 * a);
               cout << "There is an equal root" << endl;
               cout << "It is " << root1 << endl;
          }
          else
          {
               cout << "No real root" << endl;
          }
          
          cout << "Continue (yes=1/no=0)? ";
          cin >> cont;
         
     } while (cont == 1);
    return 0;
}

Question 5

#include <iostream>
using namespace std;
int main ()
{
     int number, count=0, sum=0;
     int largest = -1, smallest = 101;
     do {
           count = count + 1;
           do {
                cout << "Number " << count << "=";
                cin >> number;
                if ((number < 0) || (number > 100))
                     cout << "0-100 only, please re-enter" << endl;
           } while ((number < 0) || (number > 100));
           if (number != 0)
           {
                sum = sum + number;
                if (number > largest)
                     largest = number;
                if (number < smallest)
                     smallest = number;
           }
      } while (number != 0);
      count = count - 1;
      cout << "Count = " << count << endl;
      cout << "Sum = " << sum << endl;
      cout << "Average = " << (float)sum / (float)count << endl;
      cout << "Largest = " << largest << endl;
      cout << "Smallest = " << smallest << endl;
    return 0;
}


Question 6
#include <iostream>
#include <tgmath.h>
using namespace std;
int main ()
{
      string name;
      float tax, income, allowance, net_chargeable;
      int m, children, parent;
      int more = 1;                             // Boolean
      while (more==1)
      {
              cout << "Name? ";
              cin >> name;
              allowance = 30000;
              do {
                    cout << "Total annual income? ";
                    cin >> income;
              } while (income < 0);
              do {
                    cout <<"Marital status (1=Single, 2=Married)?  ";
                    cin >> m;
              } while ((m != 1) && (m != 2));
              if (m == 2)
              {
                    allowance = allowance + 30000;
                    do {
                          cout << "Number of children?  ";
                          cin >> children;
                    } while (children < 0);
                    if (children <= 5)
                          allowance = allowance + 10000 * children;
                    else
                          allowance = allowance + 50000;
              }
              do {
                    cout << "Number of dependent parents?  ";
                    cin >> parent;
              } while (parent < 0);
              allowance = allowance + 15000 * parent;
              net_chargeable = income - allowance;
              if (net_chargeable < 0)
                    tax = 0;
              else if (net_chargeable < 20000)
                    tax = net_chargeable * 0.1;
              else if (net_chargeable < 40000)
                     tax = 20000 * 0.1 + (net_chargeable - 20000) * 0.2;
              else
                     tax = 20000 * 0.1 + 20000 * 0.2 + (net_chargeable - 40000) * 0.3;
              if (tax > income * 0.25)
                     tax = income * 0.25;
              cout << "Tax for " << name << " is $" << int(tax) << endl;
              do {
                      cout << "Any more (yes=1/no=0)? ";
                      cin >> more;
              } while ((more != 1) && (more != 0));
            
      }
    return 0;
}