The digital SAT ships with a full Desmos graphing calculator on every math question, and using it well is the single biggest score multiplier available to test-takers. This guide covers the highest-leverage Desmos moves: solving any equation by graphing (rewrite as f(x)=0, graph it, tap the x-intercepts), finding intersections for linear and non-linear systems, reading roots and vertex directly off a quadratic, using the tilde ~ for regression, dragging sliders for parameter and 'how many solutions?' questions, using the table feature to backsolve multiple-choice, and computing mean, median, standard deviation, and quantiles with built-in list functions like mean(L), median(L), stdev(L), and quantile(L, 0.25). It also covers when NOT to reach for Desmos — the 15-second rule — and the common test-day mistakes (default zoom, decimal vs fraction display, degree vs radian mode) that quietly cost points. Includes an FAQ on Bluebook practice, calculator policy, and how much Desmos can realistically raise your score.