The similar query has been discussed big number of times in many threads and a big no. of threads are available at:
https://www.lawyersclubindia.com/forum/display.asp?cat_id=9&forum_id=49
e.g.
https://www.lawyersclubindia.com/forum/Clarity-between-gratuity-eligibility-service-5-or-4-8-yrs--28768.asp
https://www.lawyersclubindia.com/forum/Payment-of-gratuity-to-contract-employees-107832.asp#.VORdxYKqqko
and
https://www.lawyersclubindia.com/experts/Delay-in-payment-of-gratuity-520711.asp#.VORdHYKqqko
As per discussion the 240 days include all off days/holidays etc……
Section 2(c) of the Act states that "continuous service" means continuous service as defined in Section 2-A(sic.). Section 2-A of the Act is as follows :-
Andhra High Court
Kothari Industrial Corporation, ... vs Appellate Authority Under The ... on 12 September, 1997
https://indiankanoon.org/doc/762511/
5. Section 2(c) of the Act states that "continuous service" means continuous service as defined in Section 2-A(sic.). Section 2-A of the Act is as follows :-
Why don’t you work for another 22 days if your company is willing to pay Gratuity after another 22 days?
However obtain the response of the company in writing.
You can submit FormI under proper acknowledgment 30 days before effective date of resignation/LWD!