1.

uses crt;

var a,b,s:real;

begin

clrscr;

write('nhap so a: '); readln(a);

write('nhap so b: '); readln(b);

s:=a*b;

writeln('tich la: ,s:6:2);

writeln('tong la: ',a+b);

readln

end.

Câu 1:

program tong;
uses crt;
var a, b : integer;
begin
clrscr;
write(' nhap so a :');readln(a);
write(' nhap so b :');readln(b);
writeln('tong cua hai so a va b la :', a+b);
writeln('tich cua hai so a va b la :', a*b);
readln
end.

Câu 2:

program chu_nhat;
uses crt;
var a, b, c, s : integer;
begin
clrscr;
write(' nhap do dai canh a :');readln(a);
write(' nhap do dai canh b :');readln(b);
s := a*b;
c := (a+b)*2;
if (a>b) then writeln('dien tich hinh chu nhat la :',s);
if (a<b) then writeln('chu vi hinh chu nhat la :', c);
readln
end.

Câu 3: 

program cong_viec;
uses crt;
var s : real;
begin
clrscr;
write(' thoi gian hoan thanh mot cong viec la :');readln(s);
write('cong viec tren hoan thanh trong',(s/60/60):8:2,' gio', s/60:8:2,' phut',s:8:2,' giay');
readln
end.