Single, double or multiple?

I'm completing the Tourist Visa application and have reached the section asking me to select single/double/multiple entry. I have a flight to Guangzhou (27/09/2024) and will stay with my Chinese friend in Shenzhen for 7-10 days before then going to visit Hangzhou/Suzhou and Shanghai before my return flight to London from Guangzhou (19/10/2024). During my stay in Shenzhen I want to visit friends in HK again so I know I will need a double entry visa for this. On the application it says 'Expected stay for ..... day(s) per entry'. Any advice on what I should write? Thank you -