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LO: to add decimals

Next Slide. LO: to add decimals. Type your name and send:. The Basic Steps:. Next Slide. Line up the numbers by the decimal point. Fill in missing places with zeroes. Add or subtract. Addition Properties. Next Slide. Commutative Property of Addition: Numbers can be added in any order.

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LO: to add decimals

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  1. Next Slide LO: to add decimals Type your name and send:

  2. The Basic Steps: Next Slide • Line up the numbers by the decimal point. • Fill in missing places with zeroes. • Add or subtract.

  3. Addition Properties Next Slide Commutative Property of Addition: Numbers can be added in any order. Example: 5+3=3+5 Associative Property of Addition: Numbers can be grouped in any way. Example: (7+3) + 5 = 7 + (3+5)

  4. Find the nearest nice number Next Slide • Addition properties can be used to quickly find sums. • Example: What is 52 + 12.4 + 48? • We can use an addition property to quickly add this. • First, change the order: 52 + 48 + 12.4 ________________ property. • Then, group the easy numbers together: (52 + 48) + 12.4________________ property • 100 + 12.4 = 112.4 commutative associative

  5. Why Estimate? Next Slide • Before adding your numbers, use one of the estimating strategies you learned to see what the answer should be close to. • When you add, you can see if your answer is reasonable.

  6. Example: 28.9 + 13.31 Next Slide This can estimate to 30 + 13, which is 43. (nearest nice numbers) • Line up the numbers by the decimal point. • Fill in missing places with zeroes. • Add or subtract. 28.9 0 + 13.31 42.21 The answer is close to the estimate.

  7. Now your turn. Next Slide For the sum: 125.33 + 6.9 What would your estimate be? 118 132 131

  8. For the sum: 125.33 + 6.9 {estimate is 132} Which number should you write first? 125.33 6.9 It does not matter Next Slide

  9. For the sum: 125.33 + 6.9 {estimate is 132} I write down 125.33 what do I do next? Next Slide • Line up the numbers by the decimal point. • Fill in missing places with zeroes. • Add or subtract.

  10. For the sum: 125.33 + 6.9 {estimate is 132} What do you need to do now? Next Slide Add Subtract Stick zero in if you have any gaps 125.33 + 6.9 0

  11. For the sum: 125.33 + 6.9 {estimate is 132} What do you need to do now? Next Slide Add Subtract Stick a decimal in underneath then relax 125.33 + 6.90

  12. For the sum: 125.33 + 6.9 {estimate is 132} Finally add to give the answer? Next Slide 125.33 + 6.90

  13. For the sum: 125.33 + 6.9 {estimate is 132} Finally add to give the answer? Next Slide Is this near to your estimate? 125.33 + 6.90 132.23

  14. LO: to add with decimals. Last Slide A I need more practice to help me understand this and I made lots of mistakes. B I am beginning to understand this and I got many of them correct. C I really understand this and I got most of them correct.

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