*For..to..do :
Uses Crt;

Var i,n,t : integer;

Begin

 Clrscr;
 t:=0;

 Write('Nhap n : '); Readln(n);

 For i:=1 to n do If i mod 2 = 0 then t:=t+i;

 Writeln('Tong la : ',t);

 Readln

End.
*While..Do :

Uses Crt;

Var n,i,s : integer;

Begin

 Clrscr;

 s:=0; i:=1;

 Write('Nhap n : '); Readln(n);

 While i<=n do

  Begin
   If i mod 2 = 0 then s:=s+i;

   i:=i+1;

  End;

 Writeln('Tong cac so chia het cho 2 la :',s);

 Readln

End.

for...do:

uses crt;

var i,n,tong: integer;

begin

clrscr;

readln(n);

tong:=0;

for i:=1 to n do if i mod 2=0 then tong:=tong+i;

writeln(tong);

readln;

end.

while...do:

uses crt;
var n,i,tong : integer;
begin
clrscr;
tong:=0; i:=1;
readln(n);
while i<=n do
begin
if i mod 2 = 0 then tong:=tong+i;
i:=i+1;
end;
writeln(tong);
readln
end.