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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 971 · 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 47 × 30? (a) 150 (b) 1500 (c) 15000
  2. 2.Best estimate of 59 × 62? (a) 3600 (b) 36000 (c) 360
  3. 3.Best estimate of 384 + 202? (a) 600 (b) 400 (c) 800
  4. 4.Best estimate of 59 × 47? (a) 30000 (b) 3000 (c) 300
  5. 5.Best estimate of 98 × 49? (a) 5000 (b) 50000 (c) 500
  6. 6.Best estimate of 254 + 660? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 34 × 24? (a) 600 (b) 60 (c) 6000
  8. 8.Best estimate of 180 + 825? (a) 800 (b) 1200 (c) 1000
  9. 9.Best estimate of 216 + 578? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 240 + 455? (a) 500 (b) 900 (c) 700
  11. 11.Best estimate of 74 × 26? (a) 210 (b) 2100 (c) 21000
  12. 12.Best estimate of 128 + 245? (a) 300 (b) 500 (c) 100
  13. 13.Best estimate of 698 + 515? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 719 + 694? (a) 1400 (b) 1600 (c) 1200
  15. 15.Best estimate of 73 × 17? (a) 140 (b) 1400 (c) 14000
  16. 16.Best estimate of 32 × 73? (a) 2100 (b) 21000 (c) 210
  17. 17.Best estimate of 52 × 70? (a) 35000 (b) 350 (c) 3500
  18. 18.Best estimate of 57 × 17? (a) 12000 (b) 1200 (c) 120
  19. 19.Best estimate of 19 × 14? (a) 20 (b) 200 (c) 2000
  20. 20.Best estimate of 411 + 377? (a) 600 (b) 800 (c) 1000
  21. 21.Best estimate of 645 + 668? (a) 1500 (b) 1300 (c) 1100
  22. 22.Best estimate of 156 + 211? (a) 400 (b) 200 (c) 600
  23. 23.Best estimate of 80 × 83? (a) 64000 (b) 640 (c) 6400
  24. 24.Best estimate of 23 × 16? (a) 4000 (b) 400 (c) 40
  25. 25.Best estimate of 14 × 21? (a) 2000 (b) 20 (c) 200
  26. 26.Best estimate of 484 + 120? (a) 800 (b) 400 (c) 600
  27. 27.Best estimate of 542 + 279? (a) 600 (b) 800 (c) 1000
  28. 28.Best estimate of 716 + 780? (a) 1500 (b) 1300 (c) 1700
  29. 29.Best estimate of 582 + 787? (a) 1200 (b) 1600 (c) 1400
  30. 30.Best estimate of 56 × 34? (a) 180 (b) 1800 (c) 18000
  31. 31.Best estimate of 545 + 252? (a) 800 (b) 600 (c) 1000
  32. 32.Best estimate of 82 × 91? (a) 720 (b) 7200 (c) 72000
  33. 33.Best estimate of 44 × 31? (a) 120 (b) 12000 (c) 1200
  34. 34.Best estimate of 81 × 91? (a) 7200 (b) 720 (c) 72000
  35. 35.Best estimate of 88 × 60? (a) 540 (b) 5400 (c) 54000
  36. 36.Best estimate of 88 × 38? (a) 36000 (b) 3600 (c) 360
  37. 37.Best estimate of 24 × 33? (a) 600 (b) 6000 (c) 60
  38. 38.Best estimate of 181 + 590? (a) 600 (b) 1000 (c) 800
  39. 39.Best estimate of 17 × 88? (a) 180 (b) 1800 (c) 18000
  40. 40.Best estimate of 689 + 864? (a) 1800 (b) 1600 (c) 1400

Answer key

  1. 1500
  2. 3600
  3. 600
  4. 3000
  5. 5000
  6. 1000
  7. 600
  8. 1000
  9. 800
  10. 700
  11. 2100
  12. 300
  13. 1200
  14. 1400
  15. 1400
  16. 2100
  17. 3500
  18. 1200
  19. 200
  20. 800
  21. 1300
  22. 400
  23. 6400
  24. 400
  25. 200
  26. 600
  27. 800
  28. 1500
  29. 1400
  30. 1800
  31. 800
  32. 7200
  33. 1200
  34. 7200
  35. 5400
  36. 3600
  37. 600
  38. 800
  39. 1800
  40. 1600

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