НОД, ср.арифм, файлы.

function NOD(a,b: Integer): Integer;
var
  i: Integer;
begin
  for i:=1 to a do
    if (a mod i = 0) and (b mod i = 0) then result:=i;
end

function CountWords(FileName: String): Integer;
var
  f: TextFile;
  str: String;
  i: Integer;
begin
  AssignFile(f, FileName);
  Reset(f);
    Readln(f, str);
  CloseFile(f);
  result := 0;
  i := 1;
  if str <> '' then result := 1;
  while i <= length(str) do
  begin
    if str[i] = ' ' then
        begin
          str := Copy(str, i+1, length(str));
          Inc(result);
          i := 0;
        end;
    Inc(i);
  end;
end;

function MeanValue(FileName: String): Real;
var
  f: file of Real;
  count: Integer;
  x: real;
begin
  result := 0;
  count := 0 ;
  AssignFile(f, FileName);
  Reset(f);
    while not eof(f) do
      begin
        read(f, x);
        Inc(count);
        result := result + x;
      end;
  CloseFile(f);
  result := result/count;
end;