The square root button looks like a radical symbol (√) and finds the number that, when multiplied by itself, gives you your starting number

On most calculators, the square root function is marked with the symbol √. To use it, you type your number first, then press the √ button. The calculator shows you the result — the number that multiplies by itself to equal what you started with. For example, √9 = 3, because 3 × 3 = 9.

The location of the square root button varies by calculator type. On basic calculators, it is usually on the right side of the number pad. On scientific calculators, it may be a second function accessed by pressing Shift or 2nd first. On a phone calculator app, you may need to switch to scientific mode to see it.

Key Takeaways

  • The square root button is marked √ and tells you which number multiplies by itself to make your starting number.
  • On most calculators, you enter the number first, then press √ to get the answer.
  • Scientific calculators often hide the square root function behind a Shift or 2nd button that you press before √.
  • Phone calculator apps usually require you to rotate the screen or tap a menu to switch to scientific mode and see the √ button.

Where to find the square root button on different calculator types

A basic four-function calculator (addition, subtraction, multiplication, division) usually has the √ button visible on the right side, near the equals button. You do not need to press anything else first — just type your number and tap √.

A scientific calculator has more buttons and often uses a Shift or 2nd key to access less common functions. The √ button may be printed on the face, but you reach it by pressing Shift (or 2nd) first, then √. The button itself might say "√" or "sqrt". Check your calculator's manual or look for a small label above or below the button to confirm.

A phone calculator app in standard mode shows only basic functions. Rotate your phone to landscape orientation, or look for a menu icon (three horizontal lines) to switch to scientific mode. Once you do, the √ button appears on the screen.

The step-by-step process for calculating a square root

The order matters. Type the number you want the square root of first, then press the √ button. For example, to find the square root of 16: type 16, then press √. The answer is 4.

Some older or specialized calculators work the opposite way — you press √ first, then type the number. If you press √ and nothing happens, try typing your number first instead. Your calculator's manual will tell you which order it uses.

If your answer has a decimal (like 2.236 for the square root of 5), that is normal. Not every number has a whole number square root. The calculator is showing you the precise answer.

What square root actually means in real life

Square root is the opposite of squaring a number. When you square something, you multiply it by itself: 5 squared (written 5²) is 5 × 5 = 25. The square root of 25 is 5 — you are working backward from the result to find the original number.

You use square roots when you need to find the side length of a square given its area, when you are working with the Pythagorean theorem in geometry, or when you are calculating distances or standard deviation in statistics. In everyday life, you might use it to figure out the dimensions of a square room if you know its total area.

Common mistakes when using the square root button

The most common error is pressing the buttons in the wrong order. Remember: number first, then √. If you press √ and then type a number, most calculators will give you an error or an unexpected result.

Another mistake is forgetting that negative numbers do not have real square roots. If you try to find the square root of −9, a basic calculator will show an error. This is not a broken calculator — it is correct behavior. Negative square roots exist in advanced mathematics, but standard calculators do not handle them.

Some people also confuse the square root button (√) with the squaring button (usually marked x² or ^2). These do opposite things. The square root button makes numbers smaller (unless the number is between 0 and 1), while the squaring button makes them larger.

Using square root on a phone or computer

On an iPhone, open the Calculator app and rotate your phone to landscape mode. The scientific calculator view appears, and the √ button is visible on the left side. Type your number, then tap √.

On Android, the built-in calculator app usually has a menu icon (three dots or three lines) in the corner. Tap it and select "Scientific" or "Advanced". The √ button then appears on the screen.

On a computer, Windows has a built-in Calculator app. Open it, click View, and select "Scientific". The √ button is on the left. On Mac, the Calculator app in standard mode does not show √, but you can use the online calculator at calculator.com or any search engine — type "square root of 25" directly into Google and it calculates it for you.

When you might need square root in school or work

In geometry, you use square root to find the side of a square when you know the area, or to solve the Pythagorean theorem (a² + b² = c²). In algebra, square roots appear when solving quadratic equations. In statistics, you use square root to calculate standard deviation.

In construction or home improvement, you might use it to find the dimensions of a square space. In finance or science, square roots appear in formulas for calculating rates of change, distances, or other measurements. Most of the time, a calculator or computer does the work for you — you just need to know when to use it.

Frequently Asked Questions

What is the difference between square root and squaring?

Squaring multiplies a number by itself (5² = 25). Square root does the opposite — it finds which number, when multiplied by itself, gives you the starting number (√25 = 5). One makes numbers bigger, the other makes them smaller.

Why does my calculator show a decimal for some square roots?

Not every number has a whole number square root. The square root of 2 is about 1.414, and the square root of 10 is about 3.162. Your calculator is showing the accurate answer. These are called irrational numbers because they do not divide evenly.

Can I find the square root of a negative number?

No, not on a standard calculator. Negative numbers do not have real square roots. If you try, your calculator will show an error. In advanced mathematics, imaginary numbers exist, but basic calculators do not use them.

What if my calculator does not have a square root button?

Use your phone's calculator app in scientific mode, or search "square root of [your number]" in Google. You can also use an online calculator like calculator.com. Most devices have a way to calculate square root — you just may need to look in a different place.

Do I need to press equals after pressing the square root button?

Usually no. Most calculators show the answer when ready after you press √. Some older calculators may require you to press equals, but try without it first. If nothing happens, then press equals.