My 6 yr old first grade DD told me today that her friends know how to multiply and she wants me to explain it to her. Now, it's first grade and I know multiplication is not being taught yet.
3rd grade is standard but some, not all, 2nd grade teachers will start introducing it in the spring.
I'd estimate that about 3/4 of the kids in our kid's class takes math enrichment courses outside the school. The kids work at their own pace. When they master one concept, they move to the next. Its more likely that your daughter's friend is learning math outside the school.
Montessori teaches multiplication and division as a standard part of their kindergarten program. If your school has a high number of kids that enter in 1st grade, those kids will have a good foundation in those skills as at 6.