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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 270 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 66 × 38? (a) 2800 (b) 28000 (c) 280
  2. 2.Best estimate of 359 + 290? (a) 700 (b) 500 (c) 900
  3. 3.Best estimate of 189 + 585? (a) 600 (b) 1000 (c) 800
  4. 4.Best estimate of 123 + 842? (a) 700 (b) 900 (c) 1100
  5. 5.Best estimate of 183 + 480? (a) 900 (b) 700 (c) 500
  6. 6.Best estimate of 703 + 546? (a) 1200 (b) 1400 (c) 1000
  7. 7.Best estimate of 86 × 60? (a) 540 (b) 5400 (c) 54000
  8. 8.Best estimate of 635 + 793? (a) 1200 (b) 1600 (c) 1400
  9. 9.Best estimate of 31 × 37? (a) 1200 (b) 120 (c) 12000
  10. 10.Best estimate of 659 + 154? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 342 + 339? (a) 400 (b) 800 (c) 600
  12. 12.Best estimate of 86 × 91? (a) 810 (b) 8100 (c) 81000
  13. 13.Best estimate of 409 + 281? (a) 500 (b) 700 (c) 900
  14. 14.Best estimate of 97 × 24? (a) 20000 (b) 2000 (c) 200
  15. 15.Best estimate of 215 + 406? (a) 800 (b) 600 (c) 400
  16. 16.Best estimate of 20 × 50? (a) 10000 (b) 1000 (c) 100
  17. 17.Best estimate of 87 × 80? (a) 72000 (b) 720 (c) 7200
  18. 18.Best estimate of 87 × 57? (a) 54000 (b) 540 (c) 5400
  19. 19.Best estimate of 74 × 43? (a) 280 (b) 28000 (c) 2800
  20. 20.Best estimate of 230 + 207? (a) 200 (b) 600 (c) 400
  21. 21.Best estimate of 536 + 198? (a) 700 (b) 500 (c) 900
  22. 22.Best estimate of 462 + 759? (a) 1300 (b) 1500 (c) 1100
  23. 23.Best estimate of 795 + 530? (a) 1100 (b) 1300 (c) 1500
  24. 24.Best estimate of 777 + 253? (a) 1100 (b) 1300 (c) 900
  25. 25.Best estimate of 97 × 88? (a) 900 (b) 9000 (c) 90000
  26. 26.Best estimate of 71 × 20? (a) 14000 (b) 140 (c) 1400
  27. 27.Best estimate of 296 + 574? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 86 × 93? (a) 8100 (b) 810 (c) 81000
  29. 29.Best estimate of 615 + 455? (a) 1100 (b) 1300 (c) 900
  30. 30.Best estimate of 272 + 151? (a) 700 (b) 300 (c) 500
  31. 31.Best estimate of 709 + 818? (a) 1700 (b) 1500 (c) 1300
  32. 32.Best estimate of 16 × 71? (a) 14000 (b) 140 (c) 1400
  33. 33.Best estimate of 14 × 67? (a) 70 (b) 7000 (c) 700
  34. 34.Best estimate of 399 + 211? (a) 400 (b) 800 (c) 600
  35. 35.Best estimate of 17 × 21? (a) 40 (b) 400 (c) 4000
  36. 36.Best estimate of 607 + 857? (a) 1300 (b) 1500 (c) 1700
  37. 37.Best estimate of 89 × 91? (a) 81000 (b) 8100 (c) 810
  38. 38.Best estimate of 41 × 82? (a) 3200 (b) 32000 (c) 320
  39. 39.Best estimate of 96 × 54? (a) 5000 (b) 50000 (c) 500
  40. 40.Best estimate of 81 × 91? (a) 7200 (b) 720 (c) 72000

Answer key

  1. 2800
  2. 700
  3. 800
  4. 900
  5. 700
  6. 1200
  7. 5400
  8. 1400
  9. 1200
  10. 900
  11. 600
  12. 8100
  13. 700
  14. 2000
  15. 600
  16. 1000
  17. 7200
  18. 5400
  19. 2800
  20. 400
  21. 700
  22. 1300
  23. 1300
  24. 1100
  25. 9000
  26. 1400
  27. 900
  28. 8100
  29. 1100
  30. 500
  31. 1500
  32. 1400
  33. 700
  34. 600
  35. 400
  36. 1500
  37. 8100
  38. 3200
  39. 5000
  40. 7200

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