uses crt;

var i,t:integer;

begin

clrscr;

t:=0;

for i:=1 to 20 do 

  t:=t+i;

writeln(t);

readln;

end.

uses crt;

var s,i:integer;

begin

clrscr;

s:=0;

for i:=1 to 20 do 

  if i mod 2=0 then s:=s+i;

writeln('Tong cac so chan trong khoang 20 so tu nhien dau tien la: ',s);

readln;

end.

tự làm là nhanh nhất

ai đòng ý xin 1 ý kiến

1.

program tinhtong;

uses crt;

var s,i,n:integer;

begin

s:=0;

for i:=1 to 10 do s:=s+1;

writeln ('tong cua s=',s);

readln

end.

2.

program tinhtong;

uses crt;

var i,L,s:integer;

begin

write('nhap gia tri L='); readln(L);

s:=0;

for i:=1 to L do s:=s+1;

writeln('tong cua s=',s);

readln

end.

Sử dụng vòng lặp while...do:

program TinhTong20SoTNN;
var
  i, sum: integer;
begin
  i := 1;
  sum := 0;
  while i <= 20 do
  begin
    sum := sum + i;
    i := i + 1;
  end;
  writeln('Tong cua 20 so tu nhien dau tien la: ', sum);
end.

Sử dụng vòng lặp for...do:

program TinhTong20SoTNN;
var
  i, sum: integer;
begin
  sum := 0;
  for i := 1 to 20 do
    sum := sum + i;
  writeln('Tong cua 20 so tu nhien dau tien la: ', sum);
end.

#include <bits/stdc++.h>

using namespace std;

long long i,n,t;

int main()

{

cin>>n;

t=0;

for (i=1; i<=n; i++) t+=i;

cout<<t;

return 0;

}

#include <bits/stdc++.h>

using namespace std;

long long i,t;

int main()

{

t=0;

for (i=1; i<=30; i++) t+=i;

cout<<t;

return 0;

}

:))?