2 câu trả lời
uses crt;
var n,i,sum:longint;
begin
clrscr;
readln(n);
i:=12;sum:=0;
while i<=n*10+2 do
begin
inc(sum,i);
inc(i,10);
end;
write(sum);
readln;
end.
uses crt;
var i,n:integer;
s:longint;
begin clrscr;
write('nhap so n=');
readln(n);
s:=2; i:=1;
while i<=n do begin s:=s+10; i:=i+1; end;
write('tong s=', s);
readln
end.