Formulas to Put in Calculator for Act
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Reviewed by Calculator Editorial Team
Preparing for the ACT requires understanding which formulas to input into your calculator. This guide provides the essential formulas, tips for using them effectively, and examples to help you perform well on test day.
Essential ACT Calculator Formulas
The ACT Science section requires you to perform calculations using your calculator. Here are the most important formulas you'll need:
These formulas cover the majority of calculations you'll encounter in the ACT Science section. Familiarize yourself with them before test day.
How to Use These Formulas in Your Calculator
Using these formulas effectively requires proper setup and interpretation. Here's how to approach them:
1. Scientific Notation
For very large or small numbers, use scientific notation. Enter the coefficient first, then press the EE button (if available) or use the exponent function to enter the power of 10.
2. Percent Change
Calculate percent change by subtracting the original value from the new value, dividing by the original value, and multiplying by 100. Be careful with the order of operations.
3. Slope of a Line
To find the slope between two points, subtract the x-values and y-values separately, then divide the change in y by the change in x.
4. Quadratic Formula
For quadratic equations, enter the values for a, b, and c, then use the quadratic formula to find the roots. Remember to include both the positive and negative square roots.
5. Distance Formula
Use the distance formula to find the distance between two points on a coordinate plane. Square each difference, add them, then take the square root.
6. Mean
Calculate the mean by summing all values and dividing by the number of values. This gives you the average of a data set.
7. Standard Deviation
Standard deviation measures how spread out numbers are. Subtract the mean from each number, square the results, average them, then take the square root.
Tip: Always double-check your calculations, especially when dealing with negative numbers or decimals. Rounding to the nearest hundredth is typically sufficient for ACT calculations.
Common Mistakes to Avoid
Many students make these mistakes when using formulas on the ACT:
- Incorrectly entering numbers in scientific notation
- Mixing up the order of operations (PEMDAS/BODMAS)
- Forgetting to include both roots in the quadratic formula
- Using the wrong formula for the given problem
- Rounding too early in calculations
- Not checking units to ensure answers make sense
Reviewing these common errors can help you avoid them during the test.
Example Calculations
Let's walk through a sample calculation using the distance formula:
This calculation shows how to apply the distance formula step by step. Practice similar examples to build confidence.
| Formula | Example Problem | Solution |
|---|---|---|
| Scientific Notation | Express 0.00045 in scientific notation | 4.5 × 10-4 |
| Percent Change | If a stock goes from $50 to $60, what's the percent change? | 20% |
| Slope of a Line | Find the slope between (1, 2) and (4, 6) | 1 |
| Quadratic Formula | Find the roots of x² - 5x + 6 = 0 | x = 2 and x = 3 |
Frequently Asked Questions
Which calculator is allowed on the ACT?
The ACT allows the TI-30XS MultiView Scientific Calculator. It's important to familiarize yourself with this specific model before test day.
Can I use a graphing calculator?
No, only the TI-30XS calculator is permitted. Graphing calculators are not allowed.
Do I need to memorize all these formulas?
While you don't need to memorize them, you should be comfortable using them quickly during the test. Practice with the formulas regularly.
What if I don't have a calculator on test day?
You can borrow a calculator from the testing center, but it's best to bring your own to avoid any issues.