How to Find the Square Root on a Calculator

To find the square root on most calculators, you either press the square root symbol ($\sqrt{}$) followed by the number or enter the number first and then press the symbol. On scientific and graphing models, the function is often a secondary command located above the $x^2$ button, requiring the "2nd" or "Shift" key.

Finding the square root of a number is one of the most common mathematical operations, essential for everything from basic geometry to advanced engineering. While the concept of a square root—finding a number that, when multiplied by itself, gives the original value—is straightforward, the physical and digital interfaces for calculating it vary significantly across different devices. In 2026, whether you are using a legacy handheld device, a high-end graphing calculator, or a smartphone app, understanding the specific syntax and button mapping of your hardware is key to obtaining accurate results.

Understanding the Square Root Symbol and Logic

The square root symbol, known as the radical sign ($\sqrt{}$), is the universal notation for this operation. Before pressing buttons, it is helpful to understand the logic your calculator uses to process this request. Calculators generally follow one of two input logic systems: Immediate Execution (often called post-fix) or Algebraic Entry System (pre-fix).

Immediate Execution is common on basic four-function calculators. In this system, the calculator performs the action on whatever number is currently displayed. Algebraic Entry, found on scientific and graphing calculators, requires you to build the "expression" first (e.g., $\sqrt{25}$) and then press "Enter" or "Equals" to see the result.

Additionally, in advanced mathematics, you may encounter different types of roots, such as cube roots or $n$th roots. However, the standard square root button specifically refers to the principal square root of a non-negative number. If you are looking for the square root of 16, you are looking for the value 4, because $4 \times 4 = 16$.

How to Use a Basic or Standard Calculator

Basic calculators are the handheld devices often found in offices or elementary school classrooms. These typically feature a dedicated $\sqrt{x}$ or $\checkmark$ button. Because these devices have limited memory and processing power compared to their scientific counterparts, they almost always use the post-fix entry method.

Step-by-Step for Basic Models

1. Power on the device and press the "C" or "AC" button to clear any previous calculations.
2. Enter the number you wish to find the square root of. For example, if you want the square root of 144, type 1, 4, 4.
3. Press the square root button ($\sqrt{}$). On these models, the answer usually appears immediately on the screen without needing to press the equals ($=$) sign.
4. Verify the result. If you entered 144 and pressed the radical sign, the screen should now display 12.

One common mistake with basic calculators is trying to press the square root button before the number. On most standard desk calculators, pressing the $\sqrt{}$ button while the screen shows "0" will simply result in "0," and subsequent numbers typed will not be under the radical.

Navigating Scientific Calculators

Scientific calculators, such as the popular TI-30XIIS or the Casio fx-300ES Plus series, offer more complexity. These devices are designed for students and professionals who need to see the entire equation on the screen at once.

On scientific models, the square root function is frequently a secondary function. To save space on the physical keypad, manufacturers "stack" functions. The primary function (like $x^2$) is printed on the button, while the secondary function ($\sqrt{}$) is printed in a different color (often yellow, blue, or green) directly above the button on the plastic casing.

Using the Shift or 2nd Key

To access these secondary functions, you must use a modifier key, usually labeled "2nd" (Texas Instruments) or "Shift" (Casio).

1. Press the 2nd or Shift key. You may see a small indicator on the screen (like a "2nd" or "S" icon) showing that the next button press will activate the secondary function.
2. Locate the button with the radical symbol ($\sqrt{}$) above it. This is almost always the $x^2$ button.
3. Press that button. The radical symbol should appear on the screen, often followed by an open parenthesis: √(.
4. Type the number you are calculating.
5. Close the parenthesis ) for good mathematical practice, then press Enter or =.

Modern scientific calculators often feature "Natural Display" or "WriteView" technology, which makes the square root symbol look exactly as it does in a textbook, with a bar (vinculum) extending over the entire number.

Square Roots on Graphing Calculators

Graphing calculators like the TI-84 Plus CE or the Casio CG50 are essentially small computers. They handle square roots similarly to scientific calculators but with more options for formatting and multi-step equations.

On a TI-84 Plus series calculator, the square root command is accessed by pressing 2nd then x^2. Once you press these, the cursor moves under a radical sign. A common point of confusion on these advanced devices occurs when users want to continue an equation outside the square root. For example, if you want to calculate $\sqrt{16} + 5$, you must use the right arrow key to move the cursor out from under the radical bar before typing the $+ 5$. If you do not, the calculator will assume you want $\sqrt{16+5}$.

Calculating Higher-Order Roots

If your math problem requires a cube root ($\sqrt[3]{x}$) or a fourth root, graphing calculators often have a specific "Math" menu. On TI-84 models, you press the MATH button to find the 3: ³√( or 5: ˣ√ (the $n$th root) options. This allows for much more flexibility than the standard square root button.

Smartphone and Computer Calculators

The digital calculators built into modern operating systems are surprisingly powerful but often hide their best features.

iPhone (iOS)

The default iOS calculator appears as a basic four-function tool in portrait mode. If you look at it while holding the phone vertically, you might not see a square root button at all.

• Turn off Orientation Lock.
• Rotate the phone to landscape (horizontal) mode.
• The calculator will expand into a full scientific calculator. Look for the ²√x button. On iPhones, this is usually a post-fix operation: type the number, then tap the button.

Android

Most Android "Calculator" apps (including the Google-designed one) include scientific functions in the standard view or via a pull-down/slide-in menu. Look for the $\sqrt{}$ symbol. Unlike the iPhone, many Android calculators use pre-fix logic, where you tap the symbol first and then the number.

Windows and macOS

On a Windows PC, the Calculator app defaults to "Standard." Click the three horizontal lines (menu) and select "Scientific" to see more advanced root options. On macOS, opening the Calculator app and pressing Command + 2 will switch the view to Scientific. Alternatively, you can simply type "sqrt(number)" into the Spotlight search bar or the Windows search bar to get an instant result.

Advanced Methods: Using Exponents

If you encounter a calculator where the square root button is broken or missing, you can use the principles of exponents to find the answer. Mathematically, the square root of a number is the same as raising that number to the power of 0.5.

Most scientific calculators have a button for exponents, labeled as $y^x$, $x^y$, or a caret symbol (^).

1. Type the base number (e.g., 25).
2. Press the exponent button ($y^x$ or ^).
3. Type 0.5.
4. Press Enter or =.

For example, $25^{0.5} = 5$. This method is highly reliable and works on almost every programmable device, including spreadsheet software like Microsoft Excel or Google Sheets, where the formula would be =25^0.5 or =SQRT(25).

Comparison of Entry Methods by Device Type

The following table summarizes how to access and execute square root functions across various platforms as of 2026.

Troubleshooting Common Errors

Even with a high-powered calculator, errors can occur. Understanding why these happen will save time during exams or complex projects.

Negative Square Roots and "Domain Error"

If you attempt to find the square root of a negative number (e.g., $\sqrt{-16}$), most calculators will return an "Error," "Invalid Input," or "Domain Error." This is because, in the set of real numbers, you cannot multiply a number by itself to get a negative result. If you are working with complex numbers in advanced calculus, you may need to switch your graphing calculator to "Complex Mode" ($a+bi$) to get an answer involving the imaginary unit $i$.

Order of Operations (PEMDAS/BODMAS)

The radical sign acts as a grouping symbol. If you are calculating $\sqrt{9+16}$ on a scientific calculator, make sure you use parentheses if the calculator doesn't automatically extend the radical bar.

• Incorrect: √ 9 + 16 results in $3 + 16 = 19$.
• Correct: √(9+16) results in $\sqrt{25} = 5$.

Irrational Numbers and Rounding

Not all square roots are "clean" integers. The square root of 2 is an irrational number ($\approx 1.414213...$). Depending on your calculator's settings, it might provide the answer as a simplified radical (e.g., $\sqrt{8}$ becomes $2\sqrt{2}$) rather than a decimal. On Casio calculators, look for the S⇔D button to toggle between the radical form and the decimal form. On TI calculators, use the "toggle" button (two small arrows) above the Enter key.

Expert Tips for Accuracy

When performing multi-step calculations, avoid rounding the square root result before the final step. For example, if you need to calculate $5 \times \sqrt{7}$, do not find $\sqrt{7}$, round it to 2.6, and then multiply by 5. Instead, type the entire expression into your calculator as 5 * √(7). This allows the calculator to maintain maximum precision (often up to 10 or 14 decimal places) throughout the internal computation, ensuring your final answer is as accurate as possible.

Additionally, for students using Texas Instruments hardware, the official TI Education support site provides specific guidebooks for every model, which can be invaluable if your specific button layout differs from the standard configurations discussed here. Similarly, Casio's worldwide support offers emulators and manuals for their ClassWiz and graphing lines.

FAQ

Why is there no square root button on my phone calculator?

Most smartphone calculators hide the square root and other scientific functions to keep the interface simple for daily use. To find it, you usually need to disable "Orientation Lock" and rotate your phone to a horizontal (landscape) position. This triggers the scientific mode.

What is the difference between the $\sqrt{x}$ and $\sqrt[y]{x}$ buttons?

The $\sqrt{x}$ button is specifically for square roots (the number that squared equals $x$). The $\sqrt[y]{x}$ (or $^x\sqrt{y}$) button is a general-purpose root tool. It allows you to find cube roots, fourth roots, or any other root by specifying the "index" ($y$) first.

Why does my calculator show a fraction instead of a decimal for the square root?

Many modern scientific calculators (like the Casio ClassWiz or TI-30XS Multiview) default to "Math Print" or "Natural Display." This means they provide exact answers. If you want a decimal, you must press a conversion button, such as S⇔D on Casio or the double-arrow toggle on Texas Instruments.

Can I find the square root of a negative number?

On a standard calculator, this will result in an error. However, if you are using a scientific or graphing calculator with a "Complex" or "CPLX" mode enabled, the calculator can solve this using imaginary numbers (e.g., $\sqrt{-4} = 2i$).

How do I find the square root of 0?

The square root of 0 is always 0. You can simply enter 0 and press the $\sqrt{}$ button. The math holds true because $0 \times 0 = 0$.

Practical Recommendation

For the best results, identify the input logic of your specific device by testing a "perfect square" first. Type 9 then √ (or √ then 9). If the answer is 3, you have confirmed the correct sequence. If you are a student, we recommend using a scientific calculator with "Natural Display," as it reduces errors by showing the radical exactly as it appears in your homework or textbooks. For professional or quick daily tasks, the landscape-mode calculator on your smartphone is usually more than sufficient once you know how to unlock it.