Hi,I understand as a Singaporean, I am exempted from visa to visit China for 15 days. However for my travel itinerary below, do I need a visa?

Hi,

I understand as a Singaporean, I am exempted from visa to visit China for 15 days. However for my travel itinerary below, do I need a visa?

I will be in mainland China for 10 days then going to Hong kong for 1 or 2 days and back to mainland china for another 7 days.

Thanks.