Reciprocals ppt lesson 1

MATH

1. Reciprocals 7 6 6 7 1 5 2 9 4 38 9 5

2. What is a reciprocal? Webster’s dictionary defines the word as “done, given, or felt equally on both sides”. Examples: The two countries made a reciprocal trade agreement. The two business partners had a reciprocal friendship based on respect for each other.

3. But what does the word reciprocal mean in math? A reciprocal in math is a number you multiply by so that the result is 1 . Two numbers whose product is 1 are called reciprocal pairs .

4. Let’s look at some reciprocal pairs. Notice how when we multiply them, the product is 1 . 5 and 1/5 26 and 1/26 1/9 and 9

5. Here’s more examples of reciprocal pairs. Again, notice how when we multiply them, the product is 1 . 2/3 and 3/2 4/15 and 15/4 8/3 and 3/8

6. One last look at reciprocal pairs. You’re catching on!!! The product is 1! 2 ½ and 2/5 6 ⅗ and 5/33 7 ⅔ and 3/23

7. So, now that you know what reciprocals are – how do you find the reciprocal of a number? It’s so easy!!! When you hear reciprocal – think RE-FLIP-RO-CAL!!!

8. You think because you simply the fraction to get the reciprocal! RE – FLIP – RO - CAL FLIP

9. Let’s practice finding reciprocal – of some numbers. 4 15 1 6

10. Some more – 26 9 4 31

11. What if it’s a whole number? Write the whole number as a fraction, then FLIP it! 7 33 w hole number w ritten as a fraction r eciprocal

12. If it’s a whole number, write the whole number as a fraction, then FLIP it! 16 57 w hole number w ritten as a fraction r eciprocal

13. Let’s review what we’ve learned so far. Write the reciprocal for each fraction or whole number. 2/5 5/2 4 1/2 2/1 or 2 6 /10 1/3 10/6 3/1 or 3 1/4 12 5 5 47 1/12 1/55 1/47

14. Let’s review what we’ve learned so far. Find the missing fraction for each number sentence. 4 9 x = 1 ? 13 1 x ? =

15. Let’s review what we’ve learned so far. Find the missing fraction for each number sentence. 1 5 x = 1 ? 70 1 x ? =

16. There’s one more part to today’s lesson— What to do when finding the reciprocal of a mixed number ? Write the mixed number as an improper fraction Flip the improper fraction 5 ⅓ = 16 3 Now FLIP the improper fraction: 3 16 reciprocal

17. Let’s practice finding the refliprocal of some mixed numbers. 10 6 1 8 2 7 3 5 4 Improper Fraction: Reciprocal

18. Let’s practice finding the refliprocal of some mixed numbers. 30 4 1 3 2 20 7 2 1 Improper Fraction: Reciprocal

19. Let’s review what we’ve learned so far. Find the missing fraction for each number sentence. 1 5 x = 1 ? 7 1 x ? = 4 3 10