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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 889 · 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 708 + 205? (a) 700 (b) 1100 (c) 900
  2. 2.Best estimate of 29 × 77? (a) 2400 (b) 24000 (c) 240
  3. 3.Best estimate of 84 × 36? (a) 32000 (b) 3200 (c) 320
  4. 4.Best estimate of 852 + 136? (a) 800 (b) 1000 (c) 1200
  5. 5.Best estimate of 879 + 148? (a) 1000 (b) 1200 (c) 800
  6. 6.Best estimate of 834 + 690? (a) 1700 (b) 1300 (c) 1500
  7. 7.Best estimate of 18 × 13? (a) 2000 (b) 200 (c) 20
  8. 8.Best estimate of 90 × 81? (a) 7200 (b) 72000 (c) 720
  9. 9.Best estimate of 33 × 90? (a) 2700 (b) 27000 (c) 270
  10. 10.Best estimate of 68 × 33? (a) 21000 (b) 210 (c) 2100
  11. 11.Best estimate of 212 + 176? (a) 200 (b) 600 (c) 400
  12. 12.Best estimate of 810 + 681? (a) 1700 (b) 1300 (c) 1500
  13. 13.Best estimate of 424 + 466? (a) 900 (b) 1100 (c) 700
  14. 14.Best estimate of 70 × 58? (a) 42000 (b) 4200 (c) 420
  15. 15.Best estimate of 390 + 772? (a) 1200 (b) 1400 (c) 1000
  16. 16.Best estimate of 12 × 54? (a) 500 (b) 5000 (c) 50
  17. 17.Best estimate of 389 + 244? (a) 400 (b) 600 (c) 800
  18. 18.Best estimate of 676 + 834? (a) 1700 (b) 1500 (c) 1300
  19. 19.Best estimate of 695 + 393? (a) 1100 (b) 1300 (c) 900
  20. 20.Best estimate of 126 + 723? (a) 600 (b) 1000 (c) 800
  21. 21.Best estimate of 275 + 380? (a) 500 (b) 900 (c) 700
  22. 22.Best estimate of 56 × 86? (a) 5400 (b) 54000 (c) 540
  23. 23.Best estimate of 43 × 80? (a) 320 (b) 32000 (c) 3200
  24. 24.Best estimate of 547 + 721? (a) 1200 (b) 1400 (c) 1000
  25. 25.Best estimate of 500 + 407? (a) 1100 (b) 700 (c) 900
  26. 26.Best estimate of 34 × 40? (a) 1200 (b) 120 (c) 12000
  27. 27.Best estimate of 22 × 94? (a) 1800 (b) 180 (c) 18000
  28. 28.Best estimate of 46 × 44? (a) 200 (b) 20000 (c) 2000
  29. 29.Best estimate of 32 × 81? (a) 24000 (b) 240 (c) 2400
  30. 30.Best estimate of 42 × 41? (a) 16000 (b) 160 (c) 1600
  31. 31.Best estimate of 67 × 49? (a) 3500 (b) 350 (c) 35000
  32. 32.Best estimate of 177 + 183? (a) 400 (b) 600 (c) 200
  33. 33.Best estimate of 13 × 46? (a) 5000 (b) 500 (c) 50
  34. 34.Best estimate of 219 + 275? (a) 500 (b) 700 (c) 300
  35. 35.Best estimate of 531 + 502? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 557 + 681? (a) 1500 (b) 1100 (c) 1300
  37. 37.Best estimate of 613 + 521? (a) 1300 (b) 1100 (c) 900
  38. 38.Best estimate of 744 + 416? (a) 1100 (b) 900 (c) 1300
  39. 39.Best estimate of 364 + 878? (a) 1500 (b) 1300 (c) 1100
  40. 40.Best estimate of 318 + 749? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 900
  2. 2400
  3. 3200
  4. 1000
  5. 1000
  6. 1500
  7. 200
  8. 7200
  9. 2700
  10. 2100
  11. 400
  12. 1500
  13. 900
  14. 4200
  15. 1200
  16. 500
  17. 600
  18. 1500
  19. 1100
  20. 800
  21. 700
  22. 5400
  23. 3200
  24. 1200
  25. 900
  26. 1200
  27. 1800
  28. 2000
  29. 2400
  30. 1600
  31. 3500
  32. 400
  33. 500
  34. 500
  35. 1000
  36. 1300
  37. 1100
  38. 1100
  39. 1300
  40. 1000

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