Thank you for your question. The solution to your situation lies in the definition of an item that you mentioned, specifically the statement “An entire number, i.e., the initiating numeric symbol and all succeeding symbols within the numeric mode thus established”.

Using this definition as a guideline, you do not need to use a numeric terminator or a grade one terminator; you would only use a numeric indicator to start the 490 at the baseline immediately following the superscript 10. The thought process here is similar to a mixed number where the whole number is followed immediately by the fractional part starting with its numeric indicator. I have attached a file including both the Simbraille and ASCII for the proposed solution.