As a young girl, Katya Geller learned from her mother that math was the answer to everything. Now, at forty, she finds this wisdom tested: she has lost the love of her life, she is in the middle of a divorce, and has just found out that her mother is dying. Half-mad with grief, Katya turns to the unfinished notes for her mother's last textbook, hoping to find guidance in mathematical concepts. With humor, intelligence, and unfailing honesty, Katya...