Adding fractions with like denominators | Fractions | Pre-Algebra | Khan Academy

TL;DR

Learn how to add and simplify fractions by finding a common denominator and dividing both the numerator and denominator by their greatest common factor.

Transcript

So we're asked to add 3/15 plus 7/15, and then simplify the answer. So just the process when you add fractions is if they already-- well, first of all, if they're not mixed numbers, and neither of these are, and if they have the same denominator. In this example, the denominators are already the same. The denominator is 15. So if you add these two ... Read More

Key Insights

• 🍹 Adding fractions requires finding a common denominator and summing the numerators.
• 🧑‍🏭 Simplifying fractions involves dividing the numerator and denominator by their greatest common factor.
• 🆘 Diagrams can be used to visualize fractions and help understand the addition and simplification process.
• 🪈 Order does not matter when adding fractions with the same denominator.
• 💦 Simplifying fractions makes them easier to compare and work with.
• 💁 The greatest common factor (GCF) helps determine the simplified form of a fraction.
• 🪜 Least common multiple (LCM) is used when adding fractions with different denominators.

Questions & Answers

Q: How do you add fractions with different denominators?

To add fractions with different denominators, find the least common multiple (LCM) of the denominators. Then, rewrite both fractions with the LCM as the new denominator before adding the numerators.

Q: Why do we need to simplify fractions?

Simplifying fractions makes them easier to work with and understand. It involves reducing the fraction to its simplest form by dividing both the numerator and denominator by their greatest common factor.

Q: Does the order of adding fractions matter?

No, the order does not matter when adding fractions. You can add them in any order as long as the denominators are the same.

Q: How do diagrams help understand adding fractions?

Diagrams visually represent fractions and can aid in adding and simplifying fractions. By splitting a whole into equal parts, the diagrams show the relative sizes and relationships between fractions.

Summary & Key Takeaways

• To add fractions, ensure they have the same denominator. In this example, the denominators are already the same (15).

• Add the numerators together to get the sum (3 + 7 = 10).

• Simplify the fraction by finding the greatest common factor (GCF), which in this case is 5. Divide both the numerator and denominator by 5 to get the simplified fraction (10/15 becomes 2/3).