Read other letters about this article
I think this book is a terrific idea, and agree with an earlier poster that said McKellar is only aiming at a segment of young girls by writing about what she knows. Other folks can write about math for girls who "are athletes, poets, on their student council, or love animals." - folks who understand those subjects in great detail and can think up good math problems about them. McKellar shouldn't be expected to do it *all* herself.
Besides, I believe she is targeting a group of young women - heavy consumers - who really need to understand math so they can grasp the concepts of credit, interest rates, compounding and amortization. Maybe she can help some of them learn to spend wisely, payoff balances promptly and avoid massive debt.
I say brava, Danica!