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Mathematics Class Announcements and Practice Questions

Stay updated on important class information including exam dates, textbook notes, and practice questions. Explore addition methods, estimation techniques, and rounding principles. Practice problems included.

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Mathematics Class Announcements and Practice Questions

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  1. What is wrong with saying 372 base 6? What is a proper way of writing this number in base 6?

  2. Announcements • Last day to drop without a W is 9 February • First exam: 11 February • Sample questions will be posted on the website. Answers later. • Class Notes: purchase at the bookstore; you need to have them by February 11th.

  3. Let’s add in Alphabitia BCD+ DB BCD is DB is BCD + DB is

  4. You try: B0B+ABC Use the manipulatives or draw pictures to help explain your answer.

  5. Exploration 3.1 • In your groups: Do Part 1, #1 and #2a

  6. 0 2 4 6 8 10 a b c Addition of Whole Numbers • Ways to represent addition: • 1. Counters • 2. Number Line • 3. Part-Part Whole

  7. Vocabulary • A + B = C • A and B are called Addends • C is called the Sum • Since A + B = B + A every time, we give it a special name: the commutative property. • Since A + (B + C) = (A + B) + C every time, we give it a special name: the associative property.

  8. Addition and Place Value • If we have 154 + 69

  9. Mental Arithmetic • 39 + 57

  10. Mental Arithmetic • 39 + 57 • Leading digit (30 + 50) + (9 + 7) • Compensation (40 - 1) + 57 • Compensation (40 + 57) - 1 • Break and Bridge (39 + 50) + 7 • Compatible Numbers (39 + 51) + 6

  11. The name of the method is not important • Put down your pencil • 68 + 74 • How did you do this? • How might children do this?

  12. You try… • 23 + 96 • 489 + 723

  13. Estimation • Get a QUICK answer that is close but not necessarily exact!

  14. You have 5 seconds 382 + 147

  15. Estimation 382 + 147 Actual answer: 529 Ways to estimate: 380 + 150 = 530 400 + 150 - 20 = 530 375 + 150 = 525 390 + 140 = 530

  16. You try: • 45 + 87 • 391 + 1472

  17. Estimation vs. Exact Answer • Are the exact values of the addends given? • Is the exact value of the sum required? • In general: changing values (like population), measurement values (like distance), and predictions (like 35% chance of rain) are estimates

  18. Rounding • When you estimate, you are rounding to the nearest ten, hundred, million, etc. • If you round up, you are making an overestimation. • If you round down, you are making an underestimation.

  19. A problem: • I am thinking of 3 numbers whose sum is greater than 70. • Look at each statement below. Mark it as true or false. Be ready to explain why. • All three numbers are greater than 20. • If two of the number are less than 20, the other must be greater than 20.

  20. Explain the math 348+ 472 10 11 7 820

  21. Explain the math 471+ 299 10 160 600 770 How is this different from the previous example?

  22. Explain why the child made the mistake • 341 + 287 is the same as 340 + 290 + 7 + 3 • 749 + 684 is the same as 700 + 600 + 49 + 1 + 84 + 16 • 322 + 468 is the same as 320 + 460 • Would the mistake have been made if manipulatives had been used? Explain.

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