Hey amelia (that's ur name right? haha). I want to do actuarial, yes. But you choose actuarial as a major within Commerce. So I will do Commerce (Actuarial Studies)/Science. The reason why I want to pursue Commerce/Science is because doing maths + stats majors within Science helps me alot with Actuarial Studies from Commerce. (since Actuarial Studies is heavily maths-related). Also, I want to study Science majoring in maths + stats because I like maths =)
You should choose commerce/science if you reckon commerce aspect of ur degree can help you with ur science degree or vice versa. You should also consider that combination if you like both of science and commerce. =)