Ten days typically refers to 10 calendar days. However, if the 10th day falls on a weekend or a federal holiday, the deadline is extended until the next working day.
I am presuming the 10 day notice that you are referencing was issued after an answer to a complaint was not filed in a civil suit in the Court of Common Pleas. If that is the case, you should have a complaint, which will have numbered paragraphs. You must file an answer, in which you respond to each of those numbered paragraphs with your own numbered paragraph. You must also attach a verification (see link below).
The court in which you are filing may also have specific forms that must be attached.
There are many procedural hurdles that can trip you up; I thus strongly advise you to consult with an attorney.
This response given is not intended to create, nor does it create an ongoing duty to respond to questions. It does not form an attorney-client relationship, nor is it intended to be anything other than the educated opinion of the author. It should not be relied upon as legal advice. This response is based upon the limited facts provided by the posted question. To the extent additional or different facts exist, the response may change. I am licensed to practice law only in the Commonwealth of Pennsylvania. Responses are based solely on Pennsylvania law unless stated otherwise.