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A celebration of three of the female programmers of the World War II–era computer, ENIAC.

Present-tense text describes how Betty Snyder, Jean Jennings, and Kay McNulty have always been standouts: Betty inventively individualistic, Jean tenacious, and Kay perfectionistic. The highly intelligent women especially love math. During WWII, the call goes out for female mathematicians to join the war effort, computing the math problems that determine angles and timing of weapons. But there’s also a top-secret project, the ENIAC. The three heroines are among the mathematicians tapped to figure out how to program the machine and ensure its fast calculations are accurate. The machine’s a costly investment, and it’s up to the programmers to get it working in time for a demonstration for an audience of important men. With each wrong answer ENIAC generates, the pressure on the programmers grows. When they succeed—just in time—the men celebrate by congratulating themselves while the women get back to work coming up with important innovations in programming (Betty’s sort-merge datastream, Jean’s scheme to store programs, and Kay’s thrifty use of memory). The crisp, clear illustrations color-code the women yellow, red, and green for ease in keeping them straight and for showing montages. While the three are white, the forward-looking final page turn embraces the computer age with an illustration of three girls—Asian, white and chubby, and black—sharing the color-coded motif and other visual ties to the heroines’ stories.

An upbeat, necessary history.