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Published byKevin Hansen Modified over 2 years ago

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L.O.1 To be able to check with the inverse operation when using a calculator; to develop calculator skills and use a calculator effectively.

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Using a calculator work out and record in your books the answers to these: x ÷ 372 Q. How could you use the calculator to check the answers?

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You can check the answer by using the inverse operation. LOOK… = – = = = x 257 = ÷ 387 = ÷ 372 = x 372 = 5952

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Check these with a partner on a calculator: 3496 x 27 = = x 286 = ÷ 271 = – 7534 = ÷ 458 =

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L.O.2 To develop calculator skills and use a calculator effectively; to choose and use appropriate number skills to solve work problems; to check with the inverse operation when using a calculator.

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Quiz to identify calculator keys and their functions

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Key in £ £3.85 Do the sum You should see 8.2 Q. What is the answer to the question? 8.2 really means £8.20 How can we check this answer? What sum can we do using the inverse operation? Try it. We can do or

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Q. How would we enter £6.30? and 85p ? Q. How would we enter six pounds and five pence? Is it £6.5 As we cannot used mixed units in the same calculation we must enter £ p as

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Try these. Remember to check each answer using the inverse calculation.

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Volunteers needed… to explain what they did when their checking showed a wrong answer. Q. Which was the trickiest question? Why?

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LOOK… £ p + 95p = £ Q. Can this answer be right? What might have gone wrong?

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By the end of this lesson the children should be able to: Clear the display before entering a calculation; use the [+];[-]; [x] and [÷] key and decimal point to calculate; change an accidental wrong entry by using the [clear entry] key; key in and interpret money calculations; have a feel for the approximate size of an answer and check it by performing the inverse calculation.

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