program class3q1; uses wincrt;
var A, B, sum, difference, product, quotation : real;
begin
  writeln('****************************');
  writeln('*                          *');
  writeln('*  Pascal calculator       *');
  writeln('*  Input two numbers and I *');
  writeln('*  will calculate on them  *');
  writeln('*                          *');
  writeln('****************************');
  writeln('First  number : A = ?');
  readln(A);
  writeln('Second number : B = ?');
  readln(B);
  writeln;
  writeln('Calculating.....');
  writeln;
  sum := A + B;
  difference := A - B;
  product := A * B;
  quotation := A / B;
  writeln(A:0:2,' + ',B:0:2,' = ',sum:0:2);
  writeln(A:0:2,' - ',B:0:2,' = ',difference:0:2);
  writeln(A:0:2,' * ',B:0:2,' = ',product:0:2);
  writeln(A:0:2,' / ',B:0:2,' = ',quotation:0:2);
  writeln;
  writeln('Thankyou for using the program !')
end.

program class3q2; uses wincrt;
var a, b, c, d, e, f, x, y : real;
begin
  writeln('This program is to solve two simultaneous equation with the following format.');
  writeln('ax + by = c');
  writeln('dx + ey = f');
  writeln('Please enter the coefficients :');
  write('a = ');
  readln(a);
  write('b = ');
  readln(b);
  write('c = ');
  readln(c);
  write('d = ');
  readln(d);
  write('e = ');
  readln(e);
  write('f = ');
  readln(f);
  writeln;
  x := (b*f-e*c)/(b*d-a*e);
  y := (a*f-c*d)/(a*e-b*d);
  writeln('x = ',round(x),' and y = ',round(y))
end.

program class3q3; uses wincrt;
var n1, n2, n3, n4, n5 : integer;
    mean, sd : real;
begin
  randomize;
  writeln('The following random numbers are generated :');
  n1 := 1+random(25);
  n2 := 1+random(25);
  n3 := 1+random(25);
  n4 := 1+random(25);
  n5 := 1+random(25);
  writeln(n1,', ',n2,', ',n3,', ',n4,', ',n5);
  writeln('Statistics :');
  mean := (n1+n2+n3+n4+n5)/5;
  sd := sqrt((n1*n1+n2*n2+n3*n3+n4*n4+n5*n5)/5-mean*mean);
  writeln('mean  = ',mean:0:3);
  writeln('s. d. = ',sd:0:3)
end.