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Using A Calculator 1

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

BIDMAS/BODMAS (PEMDAS) and negative numbers.

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Using A Calculator 1

  1. 1. We Are Learning: <ul><li>How some of the basic function keys on a scientific calculator work </li></ul><ul><li>How to use a calculator to calculate with brackets and negative numbers </li></ul><ul><li>(brackets are also known as parentheses) </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. What Type of Calculator? <ul><li>The first thing that you need to do is work out what type of calculator you are using. </li></ul><ul><ul><li>Try typing this into your calculator: </li></ul></ul><ul><ul><li>What answer does your calculator give? </li></ul></ul><ul><ul><li>In what order has it done the calculation? </li></ul></ul>3 + 2 x 5 =
  4. 4. Basic Calculators <ul><li>Most non-scientific calculators are Left to Right calculators </li></ul><ul><li>This means that the calculator does the calculation in the order that the keys are pressed </li></ul>
  5. 5. Scientific Calculators <ul><li>Most scientific calculators are BIDMAS calculators (Some people call this BODMAS OR PEMDAS ) </li></ul><ul><li>This means that the calculator follows these rules for deciding the order for the steps in a calculation: </li></ul><ul><li>(1) Brackets (another name for parentheses) </li></ul><ul><li>(2) Indices (another name for powers or exponents) </li></ul><ul><li>(3) Division and </li></ul><ul><li>Multiplication </li></ul><ul><li>(4) Addition and </li></ul><ul><li>Subtraction </li></ul>
  6. 6. Brackets <ul><li>You can use brackets on your calculator </li></ul><ul><li>Most scientific calculators have brackets keys. Can you find them on your calculator? </li></ul><ul><li>Try this calculation: </li></ul><ul><li>What do you notice? </li></ul>3 + ( 2 x 5 = )
  7. 7. Challenge Yourself <ul><li>Here are some calculations and answers. Some are correct, but some need brackets. Can you put the brackets in the correct places? </li></ul><ul><ul><li>(a) 3 + 6 x 5 = 45 </li></ul></ul><ul><ul><li>(b) 3 + 6 x 5 = 33 </li></ul></ul><ul><ul><li>(c) 5 + 3 x 6 - 2 = 21 </li></ul></ul><ul><ul><li>(d) 5 + 3 x 6 - 2 = 32 </li></ul></ul><ul><ul><li>(e) 5 + 3 x 6 - 2 = 46 </li></ul></ul><ul><li>Use your BIDMAS calculator to help you check the answers! </li></ul>
  8. 8. Challenge Yourself: Answers <ul><li>How many did you get right? </li></ul><ul><li>(a) ( 3 + 6 ) x 5 = 45 </li></ul><ul><ul><li>(b) 3 + 6 x 5 = 33 </li></ul></ul><ul><li>In (b), you can put brackets around the 6 x 5, but you don’t really need them. </li></ul><ul><ul><li>(c) 5 + ( 3 x 6 ) - 2 = 21 </li></ul></ul><ul><ul><li>(d) ( 5 + 3 ) x ( 6 - 2 ) = 32 </li></ul></ul><ul><ul><li>(e) ( 5 + 3 ) x 6 - 2 = 46 </li></ul></ul>
  9. 9. Negative Numbers <ul><li>Your calculator should have one of these buttons: </li></ul><ul><li>Can you find this on your calculator? </li></ul>(-) +/-
  10. 10. Negative Numbers <ul><li>Let’s start with the first one. (If your calculator doesn’t have this type of button, skip this slide.) </li></ul><ul><li>Try pushing these keys: </li></ul><ul><li>What do you see on the display? </li></ul><ul><li>What happens if you use a different number instead of 5? </li></ul><ul><li>Can you work out what the (-) key does? </li></ul>(-) 5
  11. 11. Negative Numbers <ul><li>Now lets try the other type of button. Try pushing these keys: </li></ul><ul><li>What do you see on the calculator display? </li></ul><ul><li>What do you think the +/- key does? </li></ul>6 +/-
  12. 12. Negative Numbers <ul><li>Now try this: </li></ul><ul><li>Keep pushing the +/- key a few more times. </li></ul><ul><li>What happens? </li></ul><ul><li>What happens if you use a different number instead of 6? </li></ul><ul><li>What does the +/- key do? </li></ul>6 +/- +/-
  13. 13. Challenge Yourself: <ul><li>Can you work these out on your calculator? </li></ul><ul><li>(a) -2 + 7 </li></ul><ul><li>(b) -5 x -6 </li></ul><ul><li>(c) -30 ÷ 5 </li></ul><ul><li>(d) 3 + 2 x -4 </li></ul><ul><li>(e) -10 + -6 - -8 </li></ul>
  14. 14. Challenge Yourself: Answers <ul><li>How many correct answers did you get? </li></ul><ul><li>(a) -2 + 7 = 5 </li></ul><ul><li>(b) -5 x -6 = 30 </li></ul><ul><li>(c) -30 ÷ 5 = -6 </li></ul><ul><li>(d) 3 + 2 x -4 = -5 </li></ul><ul><li>(e) -10 + -6 - -8 = -8 </li></ul>
  15. 15. Summary: <ul><li>You should know that most scientific calculators follow the rules of BIDMAS (also called BODMAS or PEMDAS) </li></ul><ul><li>You should be able to use the brackets (or parentheses) keys on your calculator </li></ul><ul><li>You should be able to calculate using negative numbers </li></ul>

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