Many online calculators turn a fraction into a decimal the moment you press equals. Doing fractions on a scientific calculator properly means the opposite: type 3/4 and get 3/4 back, not 0.75, already reduced. WideMath's free online scientific calculator works this way by default, and shows a decimal only when you ask for one. If you have never used the keypad before, our general walkthrough covers MODE, SHIFT and the rest, and the full documentation lists every key; this post is about fractions specifically, with worked examples you can open for yourself.
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Entering a fraction on a scientific calculator
To enter a fraction, type the numerator, press ÷ or the dedicated fraction key, then type the denominator: 3/4 stays 3/4. WideMath keeps the result exact by default instead of converting it to a decimal, so the moment you press equals you see the fraction itself, already reduced.
WideMath actually gives you two ways to put a slash on the line. The key printed □/□ types a fraction slash directly: press 3, that key, then 4, and the entry line reads 3/4. The ÷ key does the same division, just written with the ÷ sign instead of a slash. Once you press equals, both are read exactly the same way, because underneath they are the same operator with the same rules. Neither key is smarter than the other about grouping what comes next.
That last point is the one to remember. WideMath's entry line is linear, one row of text left to right, typed the same way you would type it on a keyboard. There is no separate stacked box for a denominator that quietly protects everything you type into it. So when you divide, only the part sitting right next to ÷ is affected, unless you put brackets around the rest.
Type 1÷(2+3) and you get 1/5: the brackets force 2+3 to happen first, so you are dividing 1 by the whole sum. Drop the brackets and type 1÷2+3, and ÷ only reaches the 2: that is 1÷2, then add 3, for 7/2, seven halves, not one fifth.
Most free calculators online skip this distinction entirely and just hand back a decimal for either one. We wrote up six tests that expose a broken calculator if you want to see how bad it gets.
Mixed numbers on a scientific calculator
A mixed number like 2 3/4 needs its own key. Press SHIFT, then the same fraction key. Its shift function is printed in yellow above the key as a b/c, and pressing it opens a small entry pad with three boxes: a whole number, a numerator and a denominator, stacked the way a mixed number looks on paper. Type 2, move to the next box with the up and down arrows (the pad reminds you: ▲▼ moves between boxes, ◄► moves the cursor), type 3, move again and type 4. Press = once and the mixed number drops onto the normal single line as (2+(3/4)); press = again to work it out. The stacked pad is only for typing; nothing on this calculator displays stacked.
The answer lands as an improper fraction, 11/4 for 2 3/4, because that is the exact value. To see it back in mixed form, press SHIFT then S⇔D (its yellow shift label is a b/c⇔d/c): that flips the same result between 11/4 and 2 3/4 on the same line, and flips back if you press it again.
Entering 2 3/4 through the mixed number pad builds the expression (2+(3/4)) and lands on 11/4. Try it
Mixed numbers add, subtract, multiply and divide the same way any two numbers do: open the pad for each one, put an operator between them, and press equals.
1 3/4 + 2 1/2, typed as (1+(3/4))+(2+(1/2)), comes back as 17/4 first. SHIFT then S⇔D shows it as 4 1/4. Try it
Adding, subtracting, multiplying and dividing fractions on a scientific calculator
All four operations work the way you would expect from typing the numbers straight in. WideMath finds the result, then hands you back the reduced fraction, not the unreduced version you might get part way through doing it by hand.
| Operation | Type | Result | |
|---|---|---|---|
| Add | 3/8+5/12 | 19/24 | Try it |
| Subtract | 7/8-1/3 | 13/24 | Try it |
| Multiply | 4/9×3/8 | 1/6 | Try it |
| Divide | (3/5)/(9/10) | 2/3 | Try it |
Leave the brackets off a fraction division and the calculator has no way to know where your first fraction ends. Type 3/5/9/10 with no brackets and it works straight through, left to right: (3/5)÷9, then ÷10, for 1/150, nowhere near the 2/3 you wanted. Whenever you divide one fraction by another, bracket both of them: (3/5)/(9/10). 3/5/9/10 = 1/150
Simplifying fractions automatically
You do not simplify a fraction on a calculator like WideMath by hand. Type it, press equals, and it lands already reduced: the numerator and denominator are divided by their greatest common factor before anything reaches the screen, the same shortcut you would use with a pencil (Math Is Fun's page on simplifying fractions walks through that method, and even uses 8/12 as its own example).
Type 8/12 and the screen shows 2/3, never 8/12 and never 0.6666666667. Try it
Fraction or decimal: the S⇔D key
Every result on WideMath starts in its exact form: a fraction, a surd, or a multiple of pi, whichever applies. Press S⇔D and it redraws the same result as a decimal. Press it again and it goes back. Nothing is recalculated; you are choosing which face of the same number to look at. The FRAC pill at the top of the keypad is a shortcut for the exact same toggle.
Turning a decimal into a fraction
This is also the answer to the reverse question. Type a decimal and press equals, and if it has a clean fraction behind it, that fraction is what you see, with no extra key needed.
0.625 becomes 5/8 the moment you press equals. Try it
The interesting case is 0.1+0.2. Added as plain decimals that is 0.30000000000000004 inside almost any computer, because a tenth does not divide evenly once you are counting in binary instead of in tens, the same way a third does not divide evenly in ordinary decimal (the 0.1 + 0.2 demonstration site shows the same glitch across dozens of languages). WideMath still shows 3/10, because it rebuilds the fraction from the number rather than trusting those trailing digits, using a technique called a continued fraction to find the smallest fraction the result is really sitting on. Press S⇔D on that same result and you get a clean 0.3, not the long version: the ugly digits never actually reach the screen.
0.1+0.2 shows 3/10 exact, or 0.3 after S⇔D. Try it
Square roots, pi, and results with no small exact form
Not every exact result is a plain fraction. A square root that is not a whole number stays a surd, and a fraction of pi stays a fraction of pi, for the same reason a fraction stays a fraction: rounding early would throw away information you might need for the next step.
This only reaches so far. It covers square roots and multiples of pi, because those are the exact forms WideMath actively looks for. A cube root that is not a perfect cube, the cube root of 5 for example, has no small exact form to find, so it shows a plain 10 significant digit decimal and S⇔D has nothing to switch to: press it and nothing changes, because there is no second form to flip between.
Common mistakes with fractions on a scientific calculator
- Missing brackets around a sum used with ÷.
1÷2+3is not1÷(2+3), and3/5/9/10is not(3/5)/(9/10). If a fraction's numerator or denominator is itself an addition, subtraction, or another fraction, bracket it. - Expecting the fraction key to protect what comes after it. A stacked textbook display might treat everything you type next as part of the denominator until you move the cursor out. WideMath's line is linear, so it does not: normal left to right order applies the instant you leave the fraction key.
- Mixing up S⇔D and SHIFT then S⇔D. The bare key flips exact and decimal. Adding SHIFT flips improper and mixed. They look like the same key because they are the same key, with two different jobs.
- Assuming every root comes back as a clean surd. Only square roots get that treatment. A cube root, a fifth root, or any other root that is not a perfect square stays a decimal, and there is nothing wrong with the calculator when it does.
Worked examples at a glance
Every row below was checked against the real calculator. The decimal column is what S⇔D shows for the same result, rounded to WideMath's usual 10 significant digits.
| Input | Exact result | Decimal | |
|---|---|---|---|
1÷(2+3) | 1/5 | 0.2 | Try it |
1÷2+3 | 7/2 | 3.5 | Try it |
3/8+5/12 | 19/24 | 0.7916666667 | Try it |
7/8-1/3 | 13/24 | 0.5416666667 | Try it |
4/9×3/8 | 1/6 | 0.1666666667 | Try it |
(3/5)/(9/10) | 2/3 | 0.6666666667 | Try it |
3/5/9/10 | 1/150 | 0.006666666667 | Try it |
(2+(3/4)) | 11/4 | 2.75 | Try it |
(1+(3/4))+(2+(1/2)) | 17/4 | 4.25 | Try it |
8/12 | 2/3 | 0.6666666667 | Try it |
0.625 | 5/8 | 0.625 | Try it |
0.1+0.2 | 3/10 | 0.3 | Try it |
√(8) | 2√2 | 2.828427125 | Try it |
π÷4 | π/4 | 0.7853981634 | Try it |
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Open the scientific calculator →Questions people ask
Does WideMath show fractions stacked like a textbook calculator?
No. The entry line is linear, one row of text, so a fraction is typed and shown as a/b, for example 19/24, never as a stacked numerator over denominator. The result is still exact: only the layout is flat.
How do I simplify a fraction on a calculator?
On WideMath you do not simplify it by hand: type the fraction and press equals, and it lands already reduced to its lowest terms. Type 8/12 and the display shows 2/3, not 8/12.
How do I turn a decimal into a fraction on a calculator?
Type the decimal and press equals. If it has a clean fraction form, that fraction is what you see immediately, for example 0.625 becomes 5/8. Press S⇔D if you want to check the decimal again.
How do I enter a mixed number on a scientific calculator?
Press SHIFT then the fraction key to open the mixed number pad, labelled a b/c, fill in the whole number, numerator and denominator, and press equals. WideMath solves it as an ordinary fraction, so 2 3/4 becomes 11/4, and SHIFT then S⇔D switches that back to the mixed form.
Why did dividing two fractions give the wrong answer?
Almost always missing brackets. Typing 3/5 divided by 9/10 with no brackets divides straight through from left to right and gives 1/150. Bracket each fraction, (3/5)/(9/10), and you get the 2/3 you actually wanted.
What happens when an answer is irrational?
WideMath keeps roots and multiples of pi exact when it can: the square root of 8 shows as 2√2, not a rounded decimal. A result with no small exact form, such as a cube root that is not a perfect cube, is shown as a plain decimal instead, and S⇔D has nothing to toggle.
Sources
- Order of operations, Wikipedia, for the parentheses-first convention behind the bracket examples.
- 0.1 + 0.2 in floating point, 0.30000000000000004.com, for why 0.1+0.2 is not exactly 0.3 inside a computer.
- Continued fraction, Wikipedia, for the method behind rebuilding a decimal into its smallest matching fraction.
- Simplifying Fractions, Math Is Fun, for the greatest common factor method a calculator automates.
- Mixed Fractions, Math Is Fun, for how a mixed number relates to an improper fraction.