FormatNum - rs style

function FormatNum(n:Int64; dec:Byte=3): String;
var i:Int32; f:Double:=n;
begin
  while (abs(f) >= 1000) and Inc(i) do f /= 1000.0;
  Result := FloatToStr(Round(f,dec)) + (['','k','m','b','t','qd','qt'])[i-1];
end;

function InvFormatNum(str:String): Int64;
var
  i:Int32;
  n:Double;
  format  := ExtractFromStr(str, Letters);
  formats := ['','k','m','b','t','qd','qt'];
begin
  SetLength(str, Length(str)-Length(format));
  n := StrToFloat(str);
  while (formats[i] <> format) and Inc(i) do n *= 1000.0;
  Result := Round(n);
end;

begin
  WriteLn(FormatNum(0));
  WriteLn(FormatNum(500));
  WriteLn(FormatNum(1500));
  WriteLn(FormatNum(1200000));
  WriteLn(FormatNum(1601000000));
  WriteLn(FormatNum(-1500));

  // reversed
  WriteLn(InvFormatNum(FormatNum(0)));
  WriteLn(InvFormatNum(FormatNum(500)));
  WriteLn(InvFormatNum(FormatNum(1500)));
  WriteLn(InvFormatNum(FormatNum(1200000)));
  WriteLn(InvFormatNum(FormatNum(1601000000)));
  WriteLn(InvFormatNum(FormatNum(-1500)));
end;