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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 241 · 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 12 × 77? (a) 80 (b) 8000 (c) 800
  2. 2.Best estimate of 151 + 201? (a) 400 (b) 600 (c) 200
  3. 3.Best estimate of 830 + 381? (a) 1000 (b) 1400 (c) 1200
  4. 4.Best estimate of 459 + 380? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 92 × 24? (a) 180 (b) 18000 (c) 1800
  6. 6.Best estimate of 72 × 37? (a) 28000 (b) 280 (c) 2800
  7. 7.Best estimate of 879 + 169? (a) 1300 (b) 1100 (c) 900
  8. 8.Best estimate of 691 + 332? (a) 1000 (b) 1200 (c) 800
  9. 9.Best estimate of 551 + 546? (a) 1100 (b) 900 (c) 1300
  10. 10.Best estimate of 388 + 771? (a) 1000 (b) 1400 (c) 1200
  11. 11.Best estimate of 23 × 38? (a) 8000 (b) 800 (c) 80
  12. 12.Best estimate of 13 × 70? (a) 70 (b) 700 (c) 7000
  13. 13.Best estimate of 84 × 84? (a) 640 (b) 6400 (c) 64000
  14. 14.Best estimate of 275 + 808? (a) 900 (b) 1300 (c) 1100
  15. 15.Best estimate of 18 × 53? (a) 10000 (b) 100 (c) 1000
  16. 16.Best estimate of 760 + 256? (a) 1300 (b) 1100 (c) 900
  17. 17.Best estimate of 348 + 328? (a) 600 (b) 800 (c) 400
  18. 18.Best estimate of 49 × 27? (a) 150 (b) 1500 (c) 15000
  19. 19.Best estimate of 86 × 79? (a) 720 (b) 72000 (c) 7200
  20. 20.Best estimate of 88 × 62? (a) 5400 (b) 54000 (c) 540
  21. 21.Best estimate of 90 × 60? (a) 5400 (b) 54000 (c) 540
  22. 22.Best estimate of 57 × 69? (a) 42000 (b) 420 (c) 4200
  23. 23.Best estimate of 66 × 66? (a) 490 (b) 4900 (c) 49000
  24. 24.Best estimate of 50 × 60? (a) 3000 (b) 30000 (c) 300
  25. 25.Best estimate of 27 × 50? (a) 150 (b) 1500 (c) 15000
  26. 26.Best estimate of 291 + 856? (a) 1200 (b) 1400 (c) 1000
  27. 27.Best estimate of 21 × 93? (a) 18000 (b) 180 (c) 1800
  28. 28.Best estimate of 863 + 253? (a) 1400 (b) 1200 (c) 1000
  29. 29.Best estimate of 96 × 14? (a) 10000 (b) 1000 (c) 100
  30. 30.Best estimate of 778 + 417? (a) 1400 (b) 1200 (c) 1000
  31. 31.Best estimate of 86 × 93? (a) 810 (b) 81000 (c) 8100
  32. 32.Best estimate of 720 + 595? (a) 1300 (b) 1500 (c) 1100
  33. 33.Best estimate of 793 + 626? (a) 1200 (b) 1400 (c) 1600
  34. 34.Best estimate of 72 × 78? (a) 56000 (b) 5600 (c) 560
  35. 35.Best estimate of 54 × 20? (a) 100 (b) 10000 (c) 1000
  36. 36.Best estimate of 185 + 508? (a) 700 (b) 900 (c) 500
  37. 37.Best estimate of 30 × 82? (a) 240 (b) 2400 (c) 24000
  38. 38.Best estimate of 127 + 834? (a) 900 (b) 1100 (c) 700
  39. 39.Best estimate of 16 × 84? (a) 1600 (b) 16000 (c) 160
  40. 40.Best estimate of 654 + 782? (a) 1700 (b) 1500 (c) 1300

Answer key

  1. 800
  2. 400
  3. 1200
  4. 900
  5. 1800
  6. 2800
  7. 1100
  8. 1000
  9. 1100
  10. 1200
  11. 800
  12. 700
  13. 6400
  14. 1100
  15. 1000
  16. 1100
  17. 600
  18. 1500
  19. 7200
  20. 5400
  21. 5400
  22. 4200
  23. 4900
  24. 3000
  25. 1500
  26. 1200
  27. 1800
  28. 1200
  29. 1000
  30. 1200
  31. 8100
  32. 1300
  33. 1400
  34. 5600
  35. 1000
  36. 700
  37. 2400
  38. 900
  39. 1600
  40. 1500

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