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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 499 · 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 51 × 93? (a) 4500 (b) 45000 (c) 450
  2. 2.Best estimate of 667 + 318? (a) 1000 (b) 1200 (c) 800
  3. 3.Best estimate of 36 × 27? (a) 12000 (b) 1200 (c) 120
  4. 4.Best estimate of 47 × 41? (a) 20000 (b) 200 (c) 2000
  5. 5.Best estimate of 824 + 863? (a) 1500 (b) 1900 (c) 1700
  6. 6.Best estimate of 50 × 33? (a) 1500 (b) 150 (c) 15000
  7. 7.Best estimate of 359 + 652? (a) 1100 (b) 900 (c) 1300
  8. 8.Best estimate of 141 + 870? (a) 800 (b) 1200 (c) 1000
  9. 9.Best estimate of 91 × 86? (a) 8100 (b) 81000 (c) 810
  10. 10.Best estimate of 390 + 335? (a) 500 (b) 900 (c) 700
  11. 11.Best estimate of 592 + 804? (a) 1200 (b) 1600 (c) 1400
  12. 12.Best estimate of 139 + 535? (a) 800 (b) 600 (c) 400
  13. 13.Best estimate of 529 + 169? (a) 900 (b) 500 (c) 700
  14. 14.Best estimate of 481 + 660? (a) 1000 (b) 1400 (c) 1200
  15. 15.Best estimate of 260 + 415? (a) 500 (b) 900 (c) 700
  16. 16.Best estimate of 495 + 586? (a) 1100 (b) 900 (c) 1300
  17. 17.Best estimate of 16 × 79? (a) 160 (b) 16000 (c) 1600
  18. 18.Best estimate of 16 × 46? (a) 1000 (b) 10000 (c) 100
  19. 19.Best estimate of 130 + 760? (a) 1100 (b) 900 (c) 700
  20. 20.Best estimate of 551 + 455? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 165 + 254? (a) 300 (b) 500 (c) 700
  22. 22.Best estimate of 831 + 176? (a) 1200 (b) 800 (c) 1000
  23. 23.Best estimate of 23 × 78? (a) 16000 (b) 1600 (c) 160
  24. 24.Best estimate of 40 × 41? (a) 16000 (b) 160 (c) 1600
  25. 25.Best estimate of 23 × 86? (a) 18000 (b) 180 (c) 1800
  26. 26.Best estimate of 284 + 632? (a) 900 (b) 700 (c) 1100
  27. 27.Best estimate of 153 + 127? (a) 300 (b) 500 (c) 100
  28. 28.Best estimate of 272 + 778? (a) 1300 (b) 900 (c) 1100
  29. 29.Best estimate of 87 × 97? (a) 90000 (b) 9000 (c) 900
  30. 30.Best estimate of 320 + 654? (a) 800 (b) 1000 (c) 1200
  31. 31.Best estimate of 26 × 28? (a) 900 (b) 9000 (c) 90
  32. 32.Best estimate of 56 × 23? (a) 1200 (b) 12000 (c) 120
  33. 33.Best estimate of 560 + 376? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 43 × 33? (a) 120 (b) 12000 (c) 1200
  35. 35.Best estimate of 16 × 86? (a) 180 (b) 1800 (c) 18000
  36. 36.Best estimate of 93 × 51? (a) 450 (b) 4500 (c) 45000
  37. 37.Best estimate of 280 + 257? (a) 800 (b) 600 (c) 400
  38. 38.Best estimate of 685 + 779? (a) 1500 (b) 1700 (c) 1300
  39. 39.Best estimate of 26 × 20? (a) 600 (b) 6000 (c) 60
  40. 40.Best estimate of 485 + 791? (a) 1300 (b) 1500 (c) 1100

Answer key

  1. 4500
  2. 1000
  3. 1200
  4. 2000
  5. 1700
  6. 1500
  7. 1100
  8. 1000
  9. 8100
  10. 700
  11. 1400
  12. 600
  13. 700
  14. 1200
  15. 700
  16. 1100
  17. 1600
  18. 1000
  19. 900
  20. 1100
  21. 500
  22. 1000
  23. 1600
  24. 1600
  25. 1800
  26. 900
  27. 300
  28. 1100
  29. 9000
  30. 1000
  31. 900
  32. 1200
  33. 1000
  34. 1200
  35. 1800
  36. 4500
  37. 600
  38. 1500
  39. 600
  40. 1300

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