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Math Strategies

Desmos Graphing Calculator Tips & Tricks: Easy Ways to Solve Digital SAT Math Problems

Desmos Graphing Calculator Tips & Tricks: Easy Ways to Solve Digital SAT Math Problems

If you’re preparing for the Digital SAT, you already know that the math section isn't about basic calculations—it’s about problem-solving. That’s where Desmos, the built-in graphing calculator in the Bluebook testing app, comes in.

This powerful tool helps you:

  • Save time on complex math problems
  • Visualize equations instantly
  • Simplify tricky algebra, statistics, and geometry questions

Even though you can bring a physical calculator, Desmos Calculator offers features traditional calculators lack—like real-time graphing, sliders, and statistics functions. Mastering Desmos before test day can give you a serious edge.

If you haven't checked out the Introduction to Desmos article yet, go read it first in order to learn about the functionalities and hidden Desmos functions.

Top Ways to Use Desmos Calculator on the Digital SAT

1. Solve Systems of Equations in Seconds

Solving systems of equations the traditional way can be time-consuming. Instead, just input both equations into Desmos, and it will instantly display the intersection points—the solution to your system.

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Pro Tip: Be mindful of what the question is asking—does it require the x-coordinate, y-coordinate, or the full (x, y) solution?

2. Use Sliders to Find Missing Constants

If a problem involves an unknown constant (like "What value of k makes these lines parallel?"), Desmos lets you use sliders to dynamically adjust the value and find the answer instantly.

📌 Example: For the system below, adjust the slider for a until the two lines become parallel (no solutions).

6x - 5y = 8
y = ax + 3

When a = 1.2, the lines are parallel, and there’s no solution!

3. Graph Absolute Value and Quadratic Equations

Instead of manually solving for x, you can graph absolute value or quadratic equations and find their solutions visually by looking for x-axis intersections.

📌 Example: Solve |x - 4| = 9

  • Type it into Desmos.
  • Look for the x-intercepts (where the graph crosses the x-axis).
  • The solutions are x = -5 and x = 13.

4. Visualize Inequalities & Shading

Desmos makes inequality graphing effortless. If a problem asks whether a point is inside a shaded region, simply enter the inequalities, and Desmos will shade the solution set automatically.

📌 Example: Check if (4,5) is in the solution set of:

y < 2x - 6
3x + y > 5

The overlapping shaded region represents the solution. If the point isn’t in the darker area, it’s not a solution.

5. Quickly Find Mean, Median, & Standard Deviation

No need to manually sort numbers! Just enter your dataset into Desmos calculator and use functions like:

  • mean([data])
  • median([data])
  • stdev([data]) (for standard deviation)

📌 Example: Find the mean and median of {2, 5, 9, 10, 18, 20, 40, 38}

  • Type: mean([2,5,9,10,18,20,40,38])
  • Type: median([2,5,9,10,18,20,40,38])
  • Instantly get results without manual calculations!

6. Linear Regression for Best-Fit Lines

Desmos makes finding equations for best-fit lines effortless.

📌 Example: Suppose you’re given three points:

(1,−2.5), (-2,−13), (7,18.5)
  1. Enter them as a table.
  2. Use add regression --> linear regression to find the best-fit line.
  3. Desmos will automatically calculate the slope and y-intercept for you and give you the equation.

7. Trigonometry Functions

Instead of memorizing sin, cos, and tan values, use Desmos for quick answers.

📌 Example: Find sin(45°)

  • Type: sin(45)
  • Instantly get 0.7071 (rounded).

It also works for inverse trig functions like asin(x), acos(x), and atan(x).

8. Convert Decimals to Fractions Instantly

Ever get a decimal and need a fraction fast? Just type it into Desmos and press the fraction button.

📌 Example: Convert 0.375 to a fraction.

  • Type: 0.375
  • Click fraction conversion, and Desmos shows 3/8.

9. Speed Up Percentage Calculations

For quick percentage problems, just type them directly.

📌 Example: Find 20% of 700

  • Type: 20% 700
  • Desmos adds the word "of" directly after you type in the % sign, and when you type 700 , it instantly returns 140.

10. Work with Circles & Parabolas Easily

  • Finding the vertex of a parabola? Desmos marks it for you as soon as you graph it.

Need to graph a circle? Enter its equation in standard form:

(x - h)^2 + (y - k)^2 = r^2

and Desmos will plot it instantly.

How to Practice Using Desmos Before the SAT

Want to get comfortable with Desmos before test day? Try these strategies:

  1. Use the official SAT version of Desmos: Desmos for the Digital SAT
  2. Practice with real SAT questions and solve them using Desmos.
  3. Explore Desmos features beyond basic calculations—like lists, regressions, and transformations.

The more familiar you are, the faster you’ll be on test day.

Final Thoughts

Desmos isn’t just a calculator—it’s a test-day advantage. If you practice using it effectively, it can shave minutes off your test time and help avoid careless errors. Even better, you might be able to solve questions you have no idea how to approach.

💡 Key Takeaways:
✔ Desmos saves time by solving equations, graphing functions, and analyzing data.
✔ You should practice with Desmos before test day to maximize efficiency.
✔ Use Desmos for algebra, statistics, geometry, and trigonometry questions.

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