C1:

Uses Crt;
 Var a:array[1..1000] of integer;
        i,n,S:integer; TBC:real;
Begin
 Write(' Nhap do dai day n = '); Readln(n);
For i:= 1 to n do 
 Begin
   Write(' Nhap so thu a[',i,'] = '); Readln(a[i]);
   S:=S+a[i];
 End;
 TBC:=S/n;
Writeln('Vay trung binh cong cac so trong day = ',TBC);
Readln
End.

C2:

Uses Crt;
 Var i,n,S:integer;
Begin
 Write(' Nhap do day day N ='); Readln(n);
For i:= 1 to n do S:=S+i;
 Writeln(' Vay tong tu 1 den ',n,' = ',S);
Readln
End.

Câu 1:

uses crt;
var a:array[1..1000000] of longint;
      n,i,s:integer;
begin
      clrscr;
      s:=0;
      write('Nhap so luong phan tu: '); readln(n);
      for i:=1 to n do
            begin
                  write('Nhap phan tu thu ',i,': '); readln(a[i]);
                  s:=s+a[i];
            end;
      write('Trung binh cong cac so: ',s/n:0:2);
      readln;
end.

Câu 2:

uses crt;
var n,i,s:integer;
begin
      clrscr;
      s:=0;
      write('Nhap n: '); readln(n);
      for i:=1 to n do s:=s+i;
      write('Tong: ',s);
      readln;
end.