for...to...do
uses crt;
var i,s:integer;
begin
clrscr;
s:=0;
for i:=1 to 50 do s:=s+i*2;
writeln('s=',s);
readln
end.
while...do
uses crt;
var i,s:integer;
begin
clrscr;
i:=0; s:=0;
while i <= 100 do
begin
s:=s+i;
i:=i+2
end;
writeln('s=',s);
readln
end.