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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 80 · 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 98 × 34? (a) 3000 (b) 300 (c) 30000
  2. 2.Best estimate of 24 × 13? (a) 2000 (b) 20 (c) 200
  3. 3.Best estimate of 34 × 66? (a) 2100 (b) 21000 (c) 210
  4. 4.Best estimate of 50 × 60? (a) 30000 (b) 3000 (c) 300
  5. 5.Best estimate of 677 + 851? (a) 1800 (b) 1400 (c) 1600
  6. 6.Best estimate of 54 × 62? (a) 30000 (b) 3000 (c) 300
  7. 7.Best estimate of 847 + 690? (a) 1500 (b) 1700 (c) 1300
  8. 8.Best estimate of 666 + 777? (a) 1300 (b) 1500 (c) 1700
  9. 9.Best estimate of 86 × 31? (a) 2700 (b) 27000 (c) 270
  10. 10.Best estimate of 665 + 791? (a) 1700 (b) 1300 (c) 1500
  11. 11.Best estimate of 279 + 751? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 682 + 837? (a) 1500 (b) 1700 (c) 1300
  13. 13.Best estimate of 537 + 562? (a) 1100 (b) 1300 (c) 900
  14. 14.Best estimate of 30 × 24? (a) 60 (b) 600 (c) 6000
  15. 15.Best estimate of 50 × 22? (a) 100 (b) 1000 (c) 10000
  16. 16.Best estimate of 321 + 681? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 384 + 151? (a) 600 (b) 800 (c) 400
  18. 18.Best estimate of 49 × 19? (a) 100 (b) 10000 (c) 1000
  19. 19.Best estimate of 36 × 49? (a) 2000 (b) 20000 (c) 200
  20. 20.Best estimate of 710 + 414? (a) 1300 (b) 1100 (c) 900
  21. 21.Best estimate of 76 × 22? (a) 160 (b) 16000 (c) 1600
  22. 22.Best estimate of 606 + 237? (a) 1000 (b) 600 (c) 800
  23. 23.Best estimate of 428 + 507? (a) 700 (b) 900 (c) 1100
  24. 24.Best estimate of 697 + 122? (a) 1000 (b) 600 (c) 800
  25. 25.Best estimate of 278 + 269? (a) 800 (b) 400 (c) 600
  26. 26.Best estimate of 34 × 36? (a) 1200 (b) 12000 (c) 120
  27. 27.Best estimate of 24 × 82? (a) 160 (b) 16000 (c) 1600
  28. 28.Best estimate of 36 × 47? (a) 2000 (b) 20000 (c) 200
  29. 29.Best estimate of 58 × 58? (a) 360 (b) 3600 (c) 36000
  30. 30.Best estimate of 579 + 597? (a) 1000 (b) 1400 (c) 1200
  31. 31.Best estimate of 83 × 40? (a) 320 (b) 3200 (c) 32000
  32. 32.Best estimate of 548 + 536? (a) 800 (b) 1200 (c) 1000
  33. 33.Best estimate of 128 + 801? (a) 900 (b) 1100 (c) 700
  34. 34.Best estimate of 78 × 28? (a) 24000 (b) 240 (c) 2400
  35. 35.Best estimate of 509 + 348? (a) 600 (b) 800 (c) 1000
  36. 36.Best estimate of 354 + 187? (a) 400 (b) 600 (c) 800
  37. 37.Best estimate of 419 + 258? (a) 500 (b) 700 (c) 900
  38. 38.Best estimate of 96 × 94? (a) 9000 (b) 90000 (c) 900
  39. 39.Best estimate of 31 × 69? (a) 2100 (b) 210 (c) 21000
  40. 40.Best estimate of 66 × 56? (a) 42000 (b) 420 (c) 4200

Answer key

  1. 3000
  2. 200
  3. 2100
  4. 3000
  5. 1600
  6. 3000
  7. 1500
  8. 1500
  9. 2700
  10. 1500
  11. 1100
  12. 1500
  13. 1100
  14. 600
  15. 1000
  16. 1000
  17. 600
  18. 1000
  19. 2000
  20. 1100
  21. 1600
  22. 800
  23. 900
  24. 800
  25. 600
  26. 1200
  27. 1600
  28. 2000
  29. 3600
  30. 1200
  31. 3200
  32. 1000
  33. 900
  34. 2400
  35. 800
  36. 600
  37. 700
  38. 9000
  39. 2100
  40. 4200

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