Numerical analysis is a difficult subject on which to write open texts because it requires specialized software to program with. Sage is the best open source software option for mathematical computing. Appropriately, Sage for Undergraduates by Gregory Bard is an excellent open textbook about open computing. While Bard’s text is more about learning to program with Sage, Tea Time Numerical Analysis by Leon Q. Brin is a more traditional numerical analysis textbook. The only drawback to Brin’s offering is that the programming language used throughout is GNU Octave, another open source computing language. Although Sage would have been a better choice for open mathematics, Brin’s text is still the best open math book on numerical analysis.