function TBigInteger.CompareTo(Value: TBigInteger): Integer;
var
    I: Integer;
begin
    if (Self.Signed and not Value.Signed)
        or ((Self.Signed and Value.Signed) and (Length(Self.Numeric) > Length(Value.Numeric)))
        or (not(Self.Signed or Value.Signed) and (Length(Self.Numeric) < Length(Value.Numeric))) then
            CompareTo := -1
    else
        if (not Self.Signed and Value.Signed)
            or ((Self.Signed and Value.Signed) and (Length(Self.Numeric) < Length(Value.Numeric)))
            or (not(Self.Signed or Value.Signed) and (Length(Self.Numeric) > Length(Value.Numeric))) then
                CompareTo := +1
        else
        begin
            I := 0;
            {еще несколько while, if и тд}
        end;
end;