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Math 5 Estimating Division

Math 5 Estimating Division. Instructor: Mrs. Tew Turner. In this lesson we will learn about estimating m ultiplication using rounding. Math Warm-up What is one less than one million?. Math Warm-up What is one less than one million? 1,000,000 – 1 = 999,999.

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Math 5 Estimating Division

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  1. Math 5Estimating Division Instructor: Mrs. Tew Turner

  2. In this lesson we will learn about estimating multiplication using rounding.

  3. Math Warm-up What is one less than one million?

  4. Math Warm-up What is one less than one million? 1,000,000 – 1 = 999,999

  5. In this lesson we will answer the question: How can you estimate the quotient for division problems?

  6. Vocabulary dividend- the number to be divided 24 ÷ 4 = 6 divisor- the number that is the result of multiplying two or more factors 24 ÷ 4 = 6

  7. Vocabulary quotient - the number that is the result of dividing 24 ÷ 4 = 6

  8. Vocabulary compatible numbers – numbers that are easy to compute with mentally Ex. 21 and 3 are compatible numbers in division because 21 ÷ 3 = 7 is a fast fact.

  9. What is Division? A QUICK review! division is separating items into groups, or finding the “fair share”! Division is FASTER than separating items one by one into groups, and it is a very useful skill in day to day life! If you could NOT divide 287 ÷ 42...What would you have to do?

  10. What is Division? 287 ÷ 42=? What could you do to find the Quotient for this problem? You could separate 287 into 42 groups or You could DIVIDE 287 ÷ 42

  11. What is Division? Which would be faster if you could divide? DIVISION would be faster! We are going to look at ESTIMATION first when dividing larger numbers. This is an important skill you need.

  12. What is Division? Estimating for division is a lot like estimating for multiplication. We are going to look at ESTIMATION first when Dividing larger numbers.

  13. Estimation in Division Estimating is like asking “about how much?” There are two ways you can estimate in division.

  14. Estimation in Division One way is to round to the nearest tens or hundreds. Ex. 258 ÷ 6 Step 1: Round the dividend to the nearest tens or hundreds. 258 300

  15. Estimation in Division One way is to round to the nearest tens or hundreds. Ex. 258 ÷ 6 Step 2: Divide using the rounded dividend. 300 ÷ 6 = 50

  16. Estimation in Division One way is to round to the nearest tens or hundreds. Ex. 258 ÷ 6 300 ÷ 6 = 50 This quotient is an estimate. It should be faster to get the estimate because 30 ÷ 6 = 5, which is a fast fact, then you add the final zero, because 0 ÷ 6 = 0.

  17. Estimation in Division Another way is to use compatible numbers. Ex. 258 ÷ 6 Step 1: Find a compatible number. For this problem you would replace 258 with 240.

  18. Estimation in Division Another way is to use compatible numbers. Ex. 258 ÷ 6 How do you know what number is a compatible number?

  19. Estimation in Division Another way is to use compatible numbers. Ex. 258 ÷ 6 Use the fast facts to help you choose a compatible number. Think about fast facts for the 6 times table.

  20. Estimation in Division Another way is to use compatible numbers. Ex. 258 ÷ 6 6 x 4 = 24 So, 24 ÷ 6 = 4 This fast fact will help to solve the problem mentally.

  21. Estimation in Division Another way is to use compatible numbers. Ex. 258 ÷ 6 240 and 6 are compatible numbers, since 24 ÷ 6 = 4.

  22. Estimation in Division Another way is to use compatible numbers. Ex. 258 ÷ 6 Step 2: Use mental math to solve the problem. 240 ÷ 6 = 40

  23. Estimation in Division Another way is to use compatible numbers. Ex. 258 ÷ 6 240 ÷ 6 = 40 40 would be an underestimate since 258 was replaced with a smaller compatible number.

  24. Follow the Steps! Rounding to Estimate the Quotient Step 1: Round the dividend to the nearest tens or hundreds. Step 2: Divide using the rounded dividend. Easy as ....

  25. Follow the Steps! Using Compatible Numbers to Estimate the Quotient Step 1: Find a compatible number. Step 2: Use mental math to solve the problem. Easy as ....

  26. In your Math Notebook Use rounding to estimate the quotient 1. 834 ÷ 2 = 2. 359 ÷ 6 = 3. 187 ÷ 4 = 4. 312 ÷ 5 = 5. 975 ÷ 5 = Use your math notebook to work it out if you need to!

  27. In your Math Notebook Use compatible numbers to estimate the quotient 6. 545 ÷ 8 = 7. 317 ÷ 7 = 8. 256 ÷ 3 = 9. 433 ÷ 4 = 10. 239 ÷ 5 = Use your math notebook to work it out if you need to!

  28. In your Math Notebook Use rounding to estimate the quotient 1. 834 ÷ 2 = 800 ÷ 2 = 400 2. 359 ÷ 6 = 360 ÷ 6 = 60 3. 187 ÷ 4 = 200÷ 4 = 50 4. 312 ÷ 5 = 300÷ 5 = 60 5. 975 ÷ 5 = 1000÷ 5 = 200

  29. In your Math Notebook Use compatible numbers to estimate the quotient 6. 545 ÷ 8 = 560÷ 8 = 70 7. 317 ÷ 7 = 280÷ 7 = 40 8. 256 ÷ 3 = 240÷ 3 = 80 9. 433 ÷ 4 = 440÷ 4 = 110 10. 239 ÷ 5 = 250 ÷ 5 = 50

  30. How do you know when to round and when to use compatible numbers? Thisis one example of why you need to know your fast facts! Knowing your fast facts will help you know when to round and when to use compatible numbers.

  31. How do you know when to round and when to use compatible numbers? Which method would you use for this problem? 263 ÷ 3 =

  32. How do you know when to round and when to use compatible numbers? Does rounding help you solve this using mental math? 263 ÷ 3 = 300 ÷ 3 = ? Yes! You can use rounding to help you find an estimate to this problem.

  33. How do you know when to round and when to use compatible numbers? Does rounding help you solve this using mental math? 545 ÷ 8 = 500÷ 8 = ? No, rounding did not help to solve this mentally.

  34. How do you know when to round and when to use compatible numbers? What if we round to the nearest ten? 545 ÷ 8 = 550÷ 8 = ? No, we still can not solve this mentally.

  35. How do you know when to round and when to use compatible numbers? Now, try using compatible numbers. Remember to use your fast facts! 545 ÷ 8 =

  36. How do you know when to round and when to use compatible numbers? Think about your fast facts for the 8 times tables. 545 ÷ 8 =

  37. How do you know when to round and when to use compatible numbers? 545 ÷ 8 = 560÷ 8 = 70

  38. Problem Solving! 1. Seven friends collected cans of food for their families. The friends gathered 61 cans. Each person collected about the same number of cans. About how many cans did each student collect? Use your Math Notebook to solve and show your work.

  39. Problem Solving! 1. Seven friends collected cans of food for their families. The friends gathered 61 cans. Each person collected about the same number of cans. About how many cans did each student collect? 61 ÷ 7 = ? 63 ÷ 7 = 9 Each friend collected about 9 cans.

  40. Problem Solving! 2. Toby earned $596 in 3 months for doing laundry. If he was paid the same amount each month, about how much did he earn per month? Use your Math Notebook to solve and show your work.

  41. Problem Solving! 2. Toby earned $596 in 3 months for doing laundry. If he was paid the same amount each month, about how much did he earn per month? $596 ÷ 3 = ? $600 ÷ 3 = $200

  42. In your Math Notebook Quick Check 1. Writing to explain: If you want to use compatible numbers to estimate 262 ÷ 7, is it better to use 210 ÷ 7 or 280 ÷ 7? Explain. 2. Jorge is putting shells into 8 boxes. He wants to put the same number in each box. About how many shells could Jorge put in each box?

  43. In your Math Notebook Quick Check Writing to explain: If you want to use compatible numbers to estimate 262 ÷ 7, is it better to use 210 ÷ 7 or 280 ÷ 7? Explain. It is better to use 280 ÷ 7 because 280 is closer to 262, so the estimate will be closer to the exact solution. This makes it a better estimate.

  44. In your Math Notebook Quick Check 2. Jorge is putting 258 shells into 8 boxes. He wants to put the same number in each box. About how many shells could Jorge put in each box? 258 ÷ 8 = ? 240 ÷ 8 = 30

  45. Good Work with this lesson. Today you learned how to use estimation to divide!

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