1/

program B1;
uses crt;
var N,tr,ch,dv:integer;
Begin
    clrscr;
    write('Nhap N: ');readln(N);
    while (n<100) or (n>999) do
    begin
        write('Nhap lai n chi co 3 chu so: ');readln(n);
    end;
    tr:=n div 100;
    ch:=n mod 100;
    ch:=ch div 10;
    dv:=n mod 10;
    writeln('Hang tram: ',tr);
    writeln('Hang chuc: ',ch);
    writeln('Hang don vi: ',dv);
    readln
End.

2/

program B2;
uses crt;
var x,y,z:real;
Begin
    clrscr;
    write('x = '); readln(x);
    write('y = '); readln(y);
    z:=x;
    x:=y;
    y:=z;
    writeln('Hai so sau khi hoan doi:');
    writeln('x = ',x:2:2);
    writeln('y = ',y:2:2);
    readln
End.

3/

program B3;
uses crt;
var x,y:real;
Begin
    clrscr;
    write('x = '); readln(x);
    write('y = '); readln(y);
    x:=x+y;
    y:=x-y;
    x:=x-y;
    writeln('Hai so sau khi hoan doi:');
    writeln('x = ',x:2:2);
    writeln('y = ',y:2:2);
    readln
End.

1.

program ct;
uses crt;
var n,h100,h10:integer;
begin
    clrscr;
    writeln('Nhap N: ');readln(n);
    h100:=N div 100;
    N:=N-h100*100;
    h10:=N div 10;
    N:=N-h10*10;
    writeln('Hang tram: ',h100);
    writeln('Hang chuc: ',h10);
    writeln('Hang don vi: ',N);
    readln;
end.

2.

program ct;
uses crt;
var x,y,x2: integer;
begin
    clrscr;
    writeln('Nhap x, y:'); readln(x, y);
    x2:=x;x:=y;y:=x2;
    writeln('x = ',x,' ; y = ',y);  
    readln;
end.

3.

(mik ko bt)

____________________

#Duahauvn