Chapter 9

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## Chapter 9

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**Multiplying**Fractions Let’s make fractions our friends! Now, let’s not get all crazy with this “friend” stuff, Mr. Russler. Chapter 9**Multiplying Fractions**I have some great news when it comes to multiplying fractions… WE DON’T NEED COMMON DENOMINATORS! Sweet! Are you sure? What’s that? YES!**Multiplying Fractions**When we multiply fractions, we can use the multiplication symbol: A raised dot: Or parenthesis:**Multiplying Fractions**Terms you need to know: numerator denominator Simplify – to reduce a fraction into its simplest form. Greatest Common Factor (GCF) – the greatest number that evenly divides both numerator and denominator. Reciprocal– the fraction you get when you exchange the numerator and denominator**Multiplying Fractions**Let’s multiply the following: To multiply fractions → *Then check to see if the answer can be simplified. is reduced.**Multiplying Fractions**Let’s try another one: Replace 5 with a fraction 3 Multiply numerators → Multiply denominators→ 3 4 4) 15 = 3 12 3**Multiplying Fractions**Let’s try another one: Multiply numerators → Multiply denominators→ is , so The GCF of**RECIPROCALS**Sometimes the product of two fractions is 1 These fractions are RECIPROCALS of each other Reciprocal– the fraction you get when you flip the numerator and denominator REMEMBER … RECIPROCAL MEANS FLIP**RECIPROCALS**Find the reciprocal of each fraction**Multiplying Fractions**Your Turn! Find the reciprocal of each fraction: See how you did! 5**Multiplying**Fractions There is a shortcut!?! 9.2 Multiplication Shortcut**Multiplying Fractions**Letme show you a simplifying method called cross-cancelling Reduce or cancel the “diagonals” before you multiply. Of course I can! 1 1 1 4 I think I get it! Can you show me another one?**Multiplying Fractions**Let’s do a side-by-side. Standard method: Cross-cancel method: 1 7 6 5 Cross-cancelling is fun, and it keeps the numbers way smaller!**Multiplying Fractions**Cross-Cancelling Reduce or cancel the “diagonals” before you multiply. 1 1 6 2 5 7**Multiplying Fractions**Good luck! 3 See how you did! 1 2