What is a reasonable age t go shopping with friends?

Well, children as young as 10 years old should be able to go shopping alone or with friends. I have 2 daughters and a son. I'd often leave them at the mall on their own and they're fine. However, I think if you have a sensible and trustworthy child, then you should let him or her go shopping with friends. It will be difficult to let go, but children have to grow up and learn to deal with the rest of the world on their own.