分数計算機の使い方ガイド

What This Calculator Does

This fraction calculator is best for three common jobs: reducing one fraction to lowest terms, performing arithmetic on two fractions, and comparing which of two fractions is larger. Depending on the mode, it can also show a mixed number, a decimal, and a percentage alongside the fraction result.

That makes it especially helpful for classroom practice, homework checks, and basic number-sense work. Many users do not only want the answer. They also want to know whether the result has been reduced, whether it can be read as a mixed number, and how it looks as a decimal. The page keeps those views together.

When to Use It

• You want to reduce a fraction quickly.
• You are practicing fraction addition, subtraction, multiplication, or division.
• You need to compare which of two fractions is larger.
• You want to see the same value as a mixed number, decimal, or percentage.

Inputs Explained

Mode

The page offers simplify, operation, and compare. Deciding which task you are doing first makes the later inputs clearer and reduces mistakes around the second fraction.

Numerators and Denominators

All fraction fields must be integers, and denominators cannot be 0. If you enter a negative denominator, the page normalizes the sign so the denominator remains positive in the displayed output. That keeps the results consistent and easier to compare.

Operator

In operation mode, the page supports addition, subtraction, multiplication, and division. If the second fraction has a value of 0, it cannot be used as the divisor in division.

How the Calculation Works

The page first standardizes each fraction: it keeps the denominator positive and reduces the fraction with the greatest common divisor. In simplify mode, it shows the normalized original fraction and the fully reduced fraction, then adds a mixed number, decimal, and percentage view.

In operation mode, it applies the standard fraction rule for the selected operator and then reduces the result to lowest terms. In compare mode, it scales both fractions to a common denominator before comparing them, while also showing their decimal values for extra context.

Example

Suppose you enter 1/2 + 3/4 in operation mode. The page first performs the common-denominator addition, gets 5/4, and then shows the mixed number 1 1/4 plus the decimal 1.25. That is especially useful in study settings because you immediately see several common forms of the same answer.

If you switch to compare mode with 2/3 and 3/5, the page will scale the fractions to a shared denominator, determine which is larger, and also support that comparison with decimals.

How to Understand the Result

Original Fraction and Simplified Fraction

In simplify mode, the original fraction is the normalized form of what you entered, while the simplified fraction is the fully reduced result.

Mixed Number

A mixed number is a more readable form for an improper fraction. It is not a different value, just a different presentation.

Decimal and Percentage

These views are especially helpful when a task moves between fraction and decimal notation or when you want a more intuitive sense of size.

Comparison Result

Compare mode shows >, <, or = directly and supports that with both common-denominator reasoning and decimal interpretation.

Common Mistakes

• Typing decimals or unit text into fraction fields.
• Entering a denominator of 0.
• Dividing by a second fraction that is equal to 0.
• Treating immediate validation on incomplete input as if the calculator has failed.

FAQ

Are the results always reduced automatically?

Yes. The current page reduces every displayed result to lowest terms.

Can it compare negative fractions?

Yes. The page supports signed integer numerators or denominators and compares the normalized values correctly.

Why does simplify mode still show an original fraction?

Because it helps you compare the normalized entered form with the final reduced result, which makes the simplification easier to verify.

Can I enter mixed numbers directly?

Not currently. You need to convert a mixed number into an improper fraction before entering it.

Notes

This fraction calculator is best for ordinary integer-based fractions. It is not designed for direct mixed-number input, decimal numerators and denominators, algebraic expressions, or symbolic manipulation.

Its strength is that it combines simplification, arithmetic, and readable output formats in one place. For full handwritten-step presentation, though, it is still best used as a checking tool rather than a full replacement.