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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 426 · 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 80 × 24? (a) 160 (b) 1600 (c) 16000
  2. 2.Best estimate of 281 + 499? (a) 600 (b) 1000 (c) 800
  3. 3.Best estimate of 47 × 38? (a) 20000 (b) 2000 (c) 200
  4. 4.Best estimate of 781 + 121? (a) 900 (b) 700 (c) 1100
  5. 5.Best estimate of 843 + 431? (a) 1400 (b) 1200 (c) 1000
  6. 6.Best estimate of 58 × 36? (a) 24000 (b) 240 (c) 2400
  7. 7.Best estimate of 23 × 14? (a) 20 (b) 2000 (c) 200
  8. 8.Best estimate of 34 × 31? (a) 900 (b) 9000 (c) 90
  9. 9.Best estimate of 273 + 166? (a) 500 (b) 700 (c) 300
  10. 10.Best estimate of 681 + 475? (a) 1200 (b) 1400 (c) 1000
  11. 11.Best estimate of 84 × 27? (a) 240 (b) 2400 (c) 24000
  12. 12.Best estimate of 819 + 470? (a) 1100 (b) 1500 (c) 1300
  13. 13.Best estimate of 865 + 485? (a) 1600 (b) 1200 (c) 1400
  14. 14.Best estimate of 73 × 62? (a) 420 (b) 42000 (c) 4200
  15. 15.Best estimate of 531 + 763? (a) 1300 (b) 1100 (c) 1500
  16. 16.Best estimate of 557 + 514? (a) 1100 (b) 900 (c) 1300
  17. 17.Best estimate of 20 × 83? (a) 16000 (b) 1600 (c) 160
  18. 18.Best estimate of 623 + 151? (a) 800 (b) 600 (c) 1000
  19. 19.Best estimate of 311 + 668? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 26 × 67? (a) 21000 (b) 210 (c) 2100
  21. 21.Best estimate of 98 × 12? (a) 100 (b) 10000 (c) 1000
  22. 22.Best estimate of 301 + 451? (a) 600 (b) 1000 (c) 800
  23. 23.Best estimate of 328 + 422? (a) 700 (b) 900 (c) 500
  24. 24.Best estimate of 87 × 33? (a) 2700 (b) 27000 (c) 270
  25. 25.Best estimate of 540 + 749? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 665 + 572? (a) 1300 (b) 1100 (c) 1500
  27. 27.Best estimate of 690 + 271? (a) 800 (b) 1000 (c) 1200
  28. 28.Best estimate of 367 + 242? (a) 600 (b) 400 (c) 800
  29. 29.Best estimate of 870 + 409? (a) 1300 (b) 1100 (c) 1500
  30. 30.Best estimate of 807 + 520? (a) 1500 (b) 1100 (c) 1300
  31. 31.Best estimate of 484 + 423? (a) 1100 (b) 700 (c) 900
  32. 32.Best estimate of 806 + 851? (a) 1700 (b) 1900 (c) 1500
  33. 33.Best estimate of 554 + 487? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 36 × 36? (a) 16000 (b) 160 (c) 1600
  35. 35.Best estimate of 870 + 584? (a) 1300 (b) 1500 (c) 1700
  36. 36.Best estimate of 863 + 563? (a) 1700 (b) 1300 (c) 1500
  37. 37.Best estimate of 24 × 36? (a) 80 (b) 800 (c) 8000
  38. 38.Best estimate of 83 × 71? (a) 560 (b) 5600 (c) 56000
  39. 39.Best estimate of 393 + 324? (a) 900 (b) 700 (c) 500
  40. 40.Best estimate of 630 + 357? (a) 1200 (b) 1000 (c) 800

Answer key

  1. 1600
  2. 800
  3. 2000
  4. 900
  5. 1200
  6. 2400
  7. 200
  8. 900
  9. 500
  10. 1200
  11. 2400
  12. 1300
  13. 1400
  14. 4200
  15. 1300
  16. 1100
  17. 1600
  18. 800
  19. 1000
  20. 2100
  21. 1000
  22. 800
  23. 700
  24. 2700
  25. 1200
  26. 1300
  27. 1000
  28. 600
  29. 1300
  30. 1300
  31. 900
  32. 1700
  33. 1100
  34. 1600
  35. 1500
  36. 1500
  37. 800
  38. 5600
  39. 700
  40. 1000

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