FWIW, my DD5 in Kindergarten, IQ at the borderline-PG-range, is struggling with high 1st grade books, and flying through mid-2nd grade math. So by comparison, I'd say your daughter is more than just bright.
I agree that she sounds gifted. Her quantitative reasoning in particular appears to be a very strong area. The fact that she can see the multiplication necessary in word problems indicates more than just rote memorization.
FWIW, in re to doclori's kiddo anecdote, my oldest is not PG. Her one IQ test had scores all over the place and a semi-uncooperative kid but it would put her in the MG-HG range. Based on years of interaction with the kid, I'd say that the IQ scores were probably a bit low, but not by dozens of points. She is likely HG, but not PG. At six, she was reading books like Harry Potter and the Chronicals of Narnia and working about a grade level or two ahead in math and writing amazingly well (writing has always been a major strength of hers).
I do think that unusual academic achievement can give insight into whether a child may be gifted, but isn't always the best pin point of the level of giftedness. Mine is very focused and intense and performs very highly -- probably even more so than her IQ would predict.
