Desmos shows decimals by default, but you can switch to fractions in three ways
When you type a division problem into Desmos, the calculator returns a decimal. If you need the answer as a fraction instead — like 3/4 instead of 0.75 — you have three options: use the fraction template built into Desmos, convert a decimal result after the fact, or adjust your calculator settings. Which method works best depends on whether you want fractions for a single calculation or for everything you do in Desmos.
The fastest route for one problem is the fraction template. For ongoing work, changing your display settings takes thirty seconds and saves you from repeating the same step over and over.
Key Takeaways
- Type a division problem using the fraction template (the ÷ symbol or slash) to see the result as a fraction automatically.
- Click the wrench icon in the top right, then toggle "Exact Arithmetic" on to convert all decimal answers to fractions.
- If you already have a decimal answer, click it and select "Convert to Fraction" from the menu that appears.
- Exact Arithmetic mode works for most math problems but may show very long fractions for some calculations — you can turn it off anytime.
Using the fraction template for a single calculation
The simplest way to get a fraction answer is to enter your division using Desmos's built-in fraction format. Open Desmos in your browser or app and look at the keypad on the left side of the screen. You will see a button that looks like a fraction bar (two boxes stacked with a line between them). Click that button.
A fraction template appears in your input line with a blank numerator (top) and denominator (bottom). Type your first number in the top box and your second number in the bottom box, then press Enter. Desmos returns the answer as a simplified fraction. For example, if you enter 12 over 8, Desmos shows 3/2 rather than 1.5.
This method works for one or two problems, but if you are doing a worksheet with many fractions, you will spend more time clicking the template button than you would changing one setting.
Turning on Exact Arithmetic for all calculations
If you want Desmos to show fractions for every calculation you do, use Exact Arithmetic mode. Look for the wrench icon in the top right corner of the Desmos window (it sits next to the question mark). Click it to open the settings menu.
Scroll down until you see "Exact Arithmetic" with a toggle switch next to it. The switch is usually gray (off) by default. Click the switch to turn it blue (on). Close the settings menu by clicking the wrench icon again or clicking anywhere outside the menu.
From now on, every calculation in that Desmos session shows as a fraction. Type 5 ÷ 2 and you see 5/2 instead of 2.5. Type 1 + 1/3 and you see 4/3. This setting stays on until you turn it off again, even if you close and reopen Desmos in the same browser.
Converting a decimal answer you already have
If you have already calculated something and got a decimal, you do not have to start over. Click directly on the decimal answer in your calculation history. A small menu appears below it with several options, including "Convert to Fraction." Click that option and Desmos rewrites the answer as a fraction.
This works for any decimal Desmos has calculated, whether it came from division, a formula, or a graph. The converted fraction appears right below your original answer so you can see both versions.
When Exact Arithmetic shows very long fractions
Exact Arithmetic mode is powerful, but it can produce fractions that look strange or very long. If you calculate something like the square root of 2, Desmos might show a fraction with many digits because it is trying to express an irrational number as a fraction (which is not actually possible, so the result is an approximation). In those cases, the decimal is often clearer.
You can turn Exact Arithmetic off anytime by clicking the wrench icon again and toggling the switch back to gray. You can also leave it on and use the "Convert to Fraction" method on individual answers you want to see as decimals instead. There is no penalty for switching back and forth.
Using fractions in formulas and graphing
Fractions work the same way in formulas and graphing as they do in simple calculations. If you are graphing a line with a fractional slope, enter it as a fraction (like y = 2/3 x + 1) and Desmos handles it correctly. With Exact Arithmetic on, the output and any calculated points also appear as fractions.
If you are solving an equation and want the answer as a fraction, turn on Exact Arithmetic before you solve. Desmos then shows all intermediate steps and the final answer in fraction form, which is often easier to read and understand than a long decimal.
Frequently Asked Questions
Does Exact Arithmetic mode change my saved graphs?
No. Exact Arithmetic only changes how answers display on your screen. If you save a graph or calculation, the underlying math stays the same. When you open it again, it uses whatever display setting is active at that moment.
What if the fraction answer is still really long?
Very long fractions usually mean the decimal was already a long or repeating decimal. You can click the answer and choose "Convert to Decimal" to see the decimal form again, or just turn off Exact Arithmetic. Both options are available anytime.
Can I use fractions in my input if I type them as decimals?
Yes. Desmos converts decimals to fractions automatically when Exact Arithmetic is on. Type 0.5 and it shows 1/2. Type 0.333333 and it shows 1/3 (or a close approximation). The conversion happens behind the scenes.
Does the fraction template work on the Desmos app for phones?
Yes. The fraction button appears in the keypad on mobile devices the same way it does on desktop. Tap it to insert the fraction template, then type your numbers in the top and bottom boxes.
What happens if I turn on Exact Arithmetic and then use a decimal in my calculation?
Desmos converts the decimal to a fraction and uses that fraction in the calculation. For example, if Exact Arithmetic is on and you type 0.5 + 1, Desmos treats it as 1/2 + 1 and shows 3/2 as the answer.