Number Theory Tool

Rational Number Calculator

Free rational number calculator for adding, subtracting, multiplying, and dividing fractions. Get step-by-step solutions with automatic simplification, decimal conversion, and mixed number format. Perfect for students learning fractions and rational number operations.

Last updated: December 15, 2024

All four operations: add, subtract, multiply, divide
Automatic fraction simplification with GCD
Shows decimal and mixed number forms

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Rational Number Calculator
Perform operations with fractions and rational numbers
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Result

Simplified Fraction:

5/6

Decimal:

0.833333

Step-by-Step Solution:

Step 1: Write the fractions
1/2 + 1/3
Step 2: Find LCD = 6
Step 3: Convert to common denominator
3/6 + 2/6
Step 4: Add numerators
5/6

Rational Number Tips:

  • • Addition/Subtraction: Find common denominator (LCD)
  • • Multiplication: Multiply numerators and denominators directly
  • • Division: Multiply by the reciprocal of the second fraction
  • • Always simplify by finding the GCD of numerator and denominator
  • • Rational numbers include all fractions and integers

Rational Number Operations

Addition
Add two fractions

Example

1/2 + 1/3 = 5/6

Find LCD, convert, then add numerators

Subtraction
Subtract two fractions

Example

3/4 - 1/2 = 1/4

Find LCD, convert, then subtract numerators

Multiplication
Multiply two fractions

Example

2/3 × 3/4 = 1/2

Multiply numerators and denominators directly

Division
Divide two fractions

Example

1/2 ÷ 1/4 = 2

Multiply by the reciprocal of second fraction

Quick Example Result

1/2 + 1/3 =

Simplified

5/6

Decimal

0.833...

GCD Used

1

How to Work with Rational Numbers

Rational numbers are fundamental in mathematics, representing any number that can be expressed as a fraction of two integers. Understanding how to perform operations with rational numbers is essential for algebra, calculus, and real-world problem solving.

Addition & Subtraction Process

Step 1: Find the least common denominator (LCD)
Step 2: Convert each fraction to equivalent fraction with LCD
Step 3: Add or subtract the numerators
Step 4: Keep the common denominator
Step 5: Simplify by dividing by GCD

This systematic approach ensures accurate results for all fraction operations.

Multiplication & Division

Multiplication of rational numbers is straightforward: multiply numerators together and denominators together, then simplify. Division involves multiplying by the reciprocal of the second fraction. The reciprocal of a/b is b/a (flip the numerator and denominator).

  • Multiplication: (a/b) × (c/d) = (a×c)/(b×d)
  • Division: (a/b) ÷ (c/d) = (a/b) × (d/c) = (a×d)/(b×c)
  • Always simplify final results using the GCD
  • Check that denominators are never zero

Sources & References

  • Elementary Number Theory - David M. Burton (7th Edition)Comprehensive coverage of rational numbers and properties
  • Pre-Algebra - Richard RusczykDetailed explanations of fraction operations and rational numbers
  • Khan Academy - Fractions and Rational NumbersVideo tutorials and practice problems on rational number operations

Need help with other number operations? Check out our mixed number calculator and integer calculator.

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Rational Number Example

Step-by-Step Solution
Adding 1/2 + 1/3 using the LCD method

Given Fractions:

1/2 + 1/3

Solution Steps:

  1. Step 1: Write the fractions
  2. 1/2 + 1/3
  3. Step 2: Find LCD = 6
  4. Step 3: Convert to common denominator
  5. 3/6 + 2/6
  6. Step 4: Add numerators
  7. 5/6

Final Answer:

Simplified

5/6

Decimal

0.8333

Percent

83.33%

Multiplication Example

2/3 × 3/4

= 6/12 = 1/2

Division Example

3/4 ÷ 1/2

= 3/4 × 2/1 = 3/2

Frequently Asked Questions

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Rational Number Calculator | thecalcs