A teen with cystic fibrosis learns that her limited life can hold infinite potential. Brianna has little sentimentality about her illness, preferring to focus on the present and to try not to worry about the future. A gifted mathematician, she applies to MIT even though she knows she may not live to graduate and go on to a career. In her last year of high school, she befriends the class geek through a shared love of an acid-inspired rock album and is inspired to think about the relationships among math, life and infinity by her loquacious, eccentric math teacher. The writing, though minimalist, captures much dimension in the personalities of Brianna and those who love her. Friends whom Brianna has lost to cystic fibrosis are mentioned and remembered, but not obsessed over. Brianna is not particularly rich, beautiful, brave or intelligent (outside of math), but she understands mortality and the importance of living life rather than dwelling on the certainty of early death. An excellent next read for teens who enjoyed Jenny Downham’s Before I Die (2007). (Fiction. YA)