Adding Fractions with Different Denominators  Learn  Contents and Search  Practice  Next Lesson  Play  Previous Lesson  Explore   Feedback Practice Your Spelling List States of the United States Nations of the World   Adding Fractions with Different Denominators How to Add Fractions with different denominators: Find the Least Common Denominator (LCD) of the fractions Rename the fractions to have the LCD Add the numerators of the fractions Simplify the Fraction Example: Find the Sum of 2/9 and 3/12 Determine the Greatest Common Factor of 9 and 12 which is 3 Either multiply the denominators and divide by the GCF (9*12=108, 108/3=36) OR - Divide one of the denominators by the GCF and multiply the answer by the other denominator (9/3=3, 3*12=36) Rename the fractions to use the Least Common Denominator(2/9=8/36, 3/12=9/36) The result is 8/36 + 9/36 Add the numerators and put the sum over the LCD = 17/36 Simplify the fraction if possible. In this case it is not possible Return to Top Share Practice Add the Fractions and Reduce to Lowest Terms Reduce the answer to lowest terms and leave it as a fraction or a whole number, not a mixed number. = You have correct and   incorrect.  This is percent correct. Return to Top Tell Others About This Site AAASpell.com Practice Your Spelling List Practice Our Spelling Lists Vocabulary Practice Alphabet Practice Play Game What is it? Best Score How many correct answers can you get in 60 seconds? Extra time is awarded for each correct answer. Play longer by getting more correct. How fast can you get 20 more correct answers than wrong answers? Sudoku Timez Attack Multiplication Video Game Return to Top Explore Math Lessons by Grade Kindergarten  First Second Third Fourth Fifth Sixth Seventh Eighth Math Topics Addition Algebra Comparing Counting Decimals Division Equations Estimation Exponents Fractions Geometry Graphs Measurement Mental Math Money Multiplication Naming Numbers Patterns Percent Place Value Practical Math Properties Ratios Statistics Subtraction Math Resources Schools Teachers Parents Home Schooling Web Resources Spelling Lessons by Grade First Second Third Fourth Fifth Sixth Seventh Eighth or - Practice Your Word List Vocabulary Lessons by Grade First Second Third Fourth Fifth Sixth Seventh Eighth Geography States of the United States Nations of the World Geographical Photos WorldPlenty.com What will the future be like? Other Interests Music DVD Computer and Video Games Books Sports Toys and Games Return to Top About This Site Frequently Asked Questions Send Us Feedback About this Site Privacy Policy Purchase The Math Class CD Share| Return to Top