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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 535 · 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 41 × 40? (a) 16000 (b) 160 (c) 1600
  2. 2.Best estimate of 44 × 74? (a) 28000 (b) 2800 (c) 280
  3. 3.Best estimate of 40 × 27? (a) 12000 (b) 1200 (c) 120
  4. 4.Best estimate of 880 + 810? (a) 1900 (b) 1700 (c) 1500
  5. 5.Best estimate of 556 + 452? (a) 900 (b) 1300 (c) 1100
  6. 6.Best estimate of 73 × 66? (a) 49000 (b) 4900 (c) 490
  7. 7.Best estimate of 74 × 38? (a) 28000 (b) 280 (c) 2800
  8. 8.Best estimate of 875 + 219? (a) 1100 (b) 1300 (c) 900
  9. 9.Best estimate of 714 + 532? (a) 1000 (b) 1200 (c) 1400
  10. 10.Best estimate of 87 × 56? (a) 540 (b) 5400 (c) 54000
  11. 11.Best estimate of 46 × 28? (a) 15000 (b) 1500 (c) 150
  12. 12.Best estimate of 56 × 39? (a) 2400 (b) 240 (c) 24000
  13. 13.Best estimate of 53 × 66? (a) 35000 (b) 3500 (c) 350
  14. 14.Best estimate of 508 + 276? (a) 800 (b) 600 (c) 1000
  15. 15.Best estimate of 484 + 568? (a) 1100 (b) 1300 (c) 900
  16. 16.Best estimate of 508 + 678? (a) 1400 (b) 1200 (c) 1000
  17. 17.Best estimate of 34 × 59? (a) 18000 (b) 1800 (c) 180
  18. 18.Best estimate of 59 × 38? (a) 24000 (b) 2400 (c) 240
  19. 19.Best estimate of 63 × 92? (a) 5400 (b) 54000 (c) 540
  20. 20.Best estimate of 408 + 539? (a) 700 (b) 1100 (c) 900
  21. 21.Best estimate of 68 × 14? (a) 7000 (b) 700 (c) 70
  22. 22.Best estimate of 16 × 83? (a) 160 (b) 1600 (c) 16000
  23. 23.Best estimate of 38 × 34? (a) 120 (b) 1200 (c) 12000
  24. 24.Best estimate of 16 × 20? (a) 400 (b) 40 (c) 4000
  25. 25.Best estimate of 34 × 76? (a) 2400 (b) 24000 (c) 240
  26. 26.Best estimate of 627 + 239? (a) 1000 (b) 600 (c) 800
  27. 27.Best estimate of 432 + 512? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 28 × 66? (a) 2100 (b) 21000 (c) 210
  29. 29.Best estimate of 36 × 30? (a) 12000 (b) 120 (c) 1200
  30. 30.Best estimate of 172 + 122? (a) 500 (b) 300 (c) 100
  31. 31.Best estimate of 759 + 366? (a) 1000 (b) 1200 (c) 1400
  32. 32.Best estimate of 40 × 19? (a) 800 (b) 8000 (c) 80
  33. 33.Best estimate of 13 × 79? (a) 8000 (b) 80 (c) 800
  34. 34.Best estimate of 541 + 545? (a) 1200 (b) 1000 (c) 800
  35. 35.Best estimate of 325 + 729? (a) 1000 (b) 800 (c) 1200
  36. 36.Best estimate of 52 × 39? (a) 2000 (b) 20000 (c) 200
  37. 37.Best estimate of 862 + 223? (a) 1100 (b) 1300 (c) 900
  38. 38.Best estimate of 66 × 48? (a) 35000 (b) 3500 (c) 350
  39. 39.Best estimate of 211 + 703? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 677 + 749? (a) 1600 (b) 1200 (c) 1400

Answer key

  1. 1600
  2. 2800
  3. 1200
  4. 1700
  5. 1100
  6. 4900
  7. 2800
  8. 1100
  9. 1200
  10. 5400
  11. 1500
  12. 2400
  13. 3500
  14. 800
  15. 1100
  16. 1200
  17. 1800
  18. 2400
  19. 5400
  20. 900
  21. 700
  22. 1600
  23. 1200
  24. 400
  25. 2400
  26. 800
  27. 900
  28. 2100
  29. 1200
  30. 300
  31. 1200
  32. 800
  33. 800
  34. 1000
  35. 1000
  36. 2000
  37. 1100
  38. 3500
  39. 900
  40. 1400

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