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Estimating or Rounding

Estimating or Rounding. Rules and exercises to estimate numbers to tens, hundreds, or thousands. Rounding to Tens. When estimating to tens look at the ones digit. If the digit is 5 or more, the rounding goes up. If the ones digit is 4 or less, the rounding goes down.

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Estimating or Rounding

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  1. Estimating or Rounding Rules and exercises to estimate numbers to tens, hundreds, or thousands

  2. Rounding to Tens • When estimating to tens look at the ones digit. • If the digit is 5 or more, the rounding goes up. • If the ones digit is 4 or less, the rounding goes down. • 10, 11, 12, 13, and 14, all become 10 • 15,16, 17, 18, and 20, all become 20

  3. Now, try to estimate to tens on your own 23 121 34 234 45 365 56 829 67 283 88 507 91 756

  4. These are the right answers.How many did you get right? 23 20 121 120 34 30 234 230 45 50 365 370 56 60 829 830 67 70 283 280 88 90 507 510 91 90 756 760

  5. ESTIMATING TO HUNDREDS • When estimating to hundreds, the tens digit determine if the estimate goes up or down. • Like in the rounding to ten, if the tens digit is 5 or more, the estimate goes up. • If the tens digit is 4 or less, the estimate goes down. • 123, 135, 109, 149, all go down to 100 • 150, 161, 172, 183, 199, all go up to 200

  6. Now, you try to round to hundreds • 102 134 • 145 187 • 298 980 • 875 808 • 1,453 2,354 • 2,654 3,765 • 7,345 8,543 • 9,230 9,999

  7. How many did you get right? • 102 100 134 100 • 145 100 187 200 • 298 300 980 1,000 • 875 900 808 800 • 1,453 1,500 2,354 2,300 • 2,654 2,700 3,765 3,800 • 7,345 7,300 8,543 8,500 • 9,230 9,200 9,999 10,000

  8. Estimating Thousands • When estimating to thousands, the hundreds digit is the one that determines if the number goes up or down. • If the hundreds digit is 5 or more the estimation goes up. • If the hundreds digit is 4 or less, the estimation goes down. • 1,209, 1389, 1451, and 1499 all become 1,000 • 2,500, 2,676, 2,765, and 2999 all become 2,000

  9. Now, try to estimate to thousands • 1,598 32,456 • 3,463 47,678 • 4,875 69,087 • 5,709 78,234 • 7,089 12,909 • 4,323 87,109 • 6,675 90,534

  10. How well did you do? • 1,598 2,000 32,456 32,000 • 3,463 3,000 47,678 48,000 • 4,875 5,000 69,087 69,000 • 5,709 6,000 78,234 78,000 • 7,089 7,000 12,909 13,000 • 4,323 4,000 87,109 87,000 • 6,675 7,000 90,534 91,000

  11. Estimate these numbers to tens, hundreds, and thousands • 7, 461 • 8,071 • 9,087 • 4,690

  12. Did you get them right? • 7, 461 • 7,460 7, 500 7,000 • 8,071 • 8,070 8,100 8,000 • 9,087 • 9,090 9,100 9,000 • 4,690 • 4,690 4,700 5,000

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