Case

procedure TestCase(Numb: Int32);
begin
  Write(Numb);
  case Numb of
    0, 1, 2: WriteLn(' < 3');
    3..9:    WriteLn(' < 10');
    10, 11..18, 19: WriteLn(' < 20');
    21: {nothing};
    else WriteLn(' >= 20');
  end;
end;

var
  i: Int32;
begin
  I := 2;
  while (i < 30) do
  begin
    TestCase(i);
    i := i * 2;
  end;
end;

Output:
2 < 3
4 < 10
8 < 10
16 < 20