Adding and subtracting fractions | Fractions | Pre-Algebra | Khan Academy

TL;DR

Learn how to add and subtract fractions with the same and different denominators using real-life examples.

Transcript

Welcome to the presentation on adding and subtracting fractions. Let's get started. Let's start with what I hope shouldn't confuse you too much. This should hopefully be a relatively easy question. If I were to ask you what 1/4 plus 1/4 is. Let's think about what that means. Let's say we had a pie and it was divided into four pieces. So this is lik... Read More

Key Insights

• 🪜 Adding fractions involves adding the numerators and keeping the denominator the same.
• ❓ Subtracting fractions involves subtracting the numerators and keeping the denominator the same.
• 🪜 Fractions can be added or subtracted more easily when they have the same denominator.
• 🪜 To add or subtract fractions with different denominators, find the least common multiple (LCM) of the denominators to convert them to have the same denominator.
• 🎭 Equivalent fractions can be used to simplify fractions before performing addition or subtraction.
• 🥇 Whole numbers can be written as fractions by placing them over a denominator of 1.
• ❎ Subtraction can result in negative fractions.

Questions & Answers

Q: How do you add fractions with the same denominator?

To add fractions with the same denominator, simply add the numerators and keep the denominator the same. For example, 1/4 + 1/4 equals 2/4, which simplifies to 1/2.

Q: How do you subtract fractions with the same denominator?

To subtract fractions with the same denominator, subtract the numerators and keep the denominator the same. For example, 3/7 - 2/7 equals 1/7.

Q: How do you add fractions with different denominators?

To add fractions with different denominators, find the least common multiple (LCM) of the denominators, convert both fractions to have the same denominator, then add the numerators. For example, 1/4 + 1/2 is equivalent to 2/4 + 2/4, which equals 4/4 or 1.

Q: How do you subtract fractions with different denominators?

To subtract fractions with different denominators, follow the same steps as adding fractions with different denominators, but subtract the numerators instead. For example, 1/2 - 1/3 would become 3/6 - 2/6, which equals 1/6.

Q: Can one whole number be written as a fraction?

Yes, a whole number can be written as a fraction by putting it over a denominator of 1. For example, 1 can be written as 1/1, 2 as 2/1, and so on.

Summary & Key Takeaways

• Adding fractions with the same denominator involves adding the numerators and keeping the denominator the same.

• Subtracting fractions with the same denominator involves subtracting the numerators and keeping the denominator the same.

• When adding or subtracting fractions with different denominators, find the least common multiple of the denominators and convert both fractions to have the same denominator, then perform the operation.