Bài 1 :

uses crt;

var a, b, i : integer;

begin

clrscr;

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

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

write('cac so tu ', a ,' den ', b ,' : ');

for i := a to b do write(i:3);

readln

end.

Bài 2 :

uses crt;

var a : array[1..100] of char;

i, n, x : integer;

begin

clrscr;

write('nhap so ki tu co trong day :');readln(n);

for i := 1 to n do 

begin

write('nhap phan tu thu ', i ,' : ');readln(a[i]);

if a[i] = 'a' then x := x + 1;

end;

writeln('day co ', x ,' ki tu a ');

readln

end.

1.

uses crt;
var i,a,b,s:longint;
begin
clrscr;
   write('Nhap a= ');readln(a);
   write('Nhap b= ');readln(b);
   write('Cac so tu ',a,' den ',b,' la: ');
   for i:=a to b do
      write(i,' ');
   writeln;
   for i:=a to -1 do s:=s+i;
   writeln('Tong cac so nguyen am la: ',s);
readln
end.

2.

uses crt;
var i,n,d:longint; a:array[1..1000000]of char;
begin
clrscr;
   write('Nhap n= ');readln(n);
   for i:=1 to n do
      begin
         write('Ki tu thu ',i,': ');readln(a[i]);
         if a[i]='a' then inc(d);
      end;
   write('Day co ',d,' ki tu a');
readln
end.