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# Using A Calculator 2

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Presenation originally wrtten to support the teaching of OCR GCSE Mathematics Module 6, chapter 1: Using a calculator effectively.

Calculating powers and roots

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• This presentation was adapted from one that I used with my class. There is also a set of work cards, designed for students to use in groups as they work on a chapter. All the resources are available to download via www.morethanmaths.com/m6
• ### Using A Calculator 2

1. 1. We Are Learning: <ul><li>How to use the power keys on a scientific calculator </li></ul><ul><li>(powers are also known as indices or exponents) </li></ul><ul><li>How to use the root keys on a scientific calculator </li></ul>
2. 2. Important Advice: <ul><li>Different makes and models of calculator have different designs of keys. Yours might not look like the examples in this presentation. </li></ul><ul><li>Ask your teacher for advice about </li></ul><ul><li>how your calculator works. </li></ul><ul><li>This presentation was made for students in the United Kingdom. I’ve tried to include alternative terms for students from outside the UK –sorry if there are any problems! </li></ul>
3. 3. The x 2 key <ul><li>Your calculator probably has a button like this: </li></ul><ul><li>Can you find this on your calculator? </li></ul><ul><li>Watch out! It might be a second function, if it is you will need to push shift or 2ndF to make it work. </li></ul>X 2
4. 4. The x 2 key <ul><li>Try pushing these keys: </li></ul><ul><li>You should see the answer 16. </li></ul><ul><li>What calculation do you think the x 2 button does? </li></ul><ul><li>Try changing the number 4 to something else and do the calculation again. </li></ul><ul><li>What happens now? </li></ul>4 X 2 =
5. 5. The x 2 key <ul><li>Can you work these out on your calculator? </li></ul><ul><li>(a) 5 2 </li></ul><ul><li>(b) 8 2 </li></ul><ul><li>(c) 25 2 </li></ul><ul><li>(d) 45 2 </li></ul><ul><li>(e) 120 2 </li></ul>
6. 6. The x 2 key : Answers <ul><li>How many did you get right? </li></ul><ul><li>(a) 5 2 = 25 </li></ul><ul><li>(b) 8 2 = 64 </li></ul><ul><li>(c) 25 2 = 625 </li></ul><ul><li>(d) 45 2 = 2025 </li></ul><ul><li>(e) 120 2 = 14400 </li></ul>
7. 7. The y x key <ul><li>Can you find a button your calculator that looks like one of these? </li></ul><ul><li>They all do the same thing, but some makes of calculator use different designs to others. </li></ul><ul><li>Watch out! This might be a second function, if it is you will need to push shift or 2ndF to make it work. </li></ul>y x X y ^
8. 8. The y x key <ul><li>Try pushing these keys. </li></ul><ul><li>What answer do you get? </li></ul><ul><li>What calculation might have given that answer? </li></ul>4 y x 2 =
9. 9. The y x key <ul><li>Now try pushing these keys. </li></ul><ul><li>What answer do you get? </li></ul><ul><li>What calculation might have given that answer? </li></ul><ul><li>Try it again with some different numbers. </li></ul><ul><li>Can you work out what this button does? </li></ul>2 y x 3 =
10. 10. The y x key <ul><li>These buttons work out powers or exponents </li></ul><ul><li>To calculate 5 3 , push these keys: </li></ul>y x X y ^ 5 y x 3 =
11. 11. The y x key: Test Yourself <ul><li>Check that you know how to use this key by doing these calculations. </li></ul><ul><li>If you get the correct answer, then you are using your calculator correctly. </li></ul><ul><li>(a) 3 4 (correct answer: 81) </li></ul><ul><li>(b) 2 5 (correct answer: 32) </li></ul><ul><li>(c) 6 3 (correct answer: 216) </li></ul><ul><li>(d) 12 4 (correct answer: 20736) </li></ul><ul><li>(e) 15 5 (correct answer: 759375) </li></ul>
12. 12. The √ _ key <ul><li>Your calculator should have a button like this: </li></ul><ul><li>Can you find this key on your calculator? </li></ul>√ _
13. 13. The √ _ key <ul><li>Try pushing these keys. </li></ul><ul><li>You should see the answer 3. </li></ul><ul><li>What calculation do you think the √ _ button does? </li></ul>HINT: Some calculators work in a slightly different way. If you don’t get the answer 3, try keying 9 in first and then press √ _ 9 = √ _
14. 14. The √ _ key <ul><li>Now try these: </li></ul><ul><li>What calculation do you think the √ _ button does? </li></ul>2 = √ _ 5 1 = √ _ 6
15. 15. The √ _ key <ul><li>The √ _ button is used to calculate square roots </li></ul><ul><li>Did you manage to work that out for yourself? </li></ul>√ _
16. 16. The √ _ key <ul><li>Can you work these out on your calculator? </li></ul><ul><li>(a) </li></ul><ul><li>(b) </li></ul><ul><li>(c) </li></ul><ul><li>(d) </li></ul><ul><li>(e) </li></ul>
17. 17. The √ _ key: answers <ul><li>How many correct answers did you get? </li></ul><ul><li>(a) = 8 </li></ul><ul><li>(b) = 11 </li></ul><ul><li>(c) = 15 </li></ul><ul><li>(d) = 20 </li></ul><ul><li>(e) = 23 </li></ul>
18. 18. Finding roots <ul><li>Can you find a button your calculator that looks like one of these? </li></ul><ul><li>Watch out! It might be a second function, if it is you will need to push shift or 2ndF to make it work. </li></ul>
19. 19. Finding roots <ul><li>Try pushing these keys. </li></ul><ul><li>What answer do you get? </li></ul><ul><li>What calculation might have given that answer? </li></ul>3 8 =
20. 20. Finding roots <ul><li>Now try pushing these keys. </li></ul><ul><li>What answer do you get? </li></ul><ul><li>What calculation might have given that answer? </li></ul>6 3 = 4
21. 21. Finding roots <ul><li>Try it again using these keys. </li></ul><ul><li>What answer do you get? </li></ul><ul><li>Can you work out what this button does? </li></ul>1 4 = 6
22. 22. Finding roots <ul><li>This will calculate the cube root of 64: </li></ul><ul><li>= 4 </li></ul><ul><li>Did you manage to work that out for yourself? </li></ul>6 3 = 4
23. 23. Summary: <ul><li>You should know how to use your calculator to find squares and square roots </li></ul><ul><li>You should know which key calculates powers (exponents) and how to use it </li></ul><ul><li>You should know which key calculates roots and how to use it </li></ul>