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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 418 · 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 526 + 430? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 90 × 36? (a) 360 (b) 3600 (c) 36000
  3. 3.Best estimate of 66 × 91? (a) 630 (b) 6300 (c) 63000
  4. 4.Best estimate of 60 × 36? (a) 24000 (b) 240 (c) 2400
  5. 5.Best estimate of 829 + 631? (a) 1400 (b) 1600 (c) 1200
  6. 6.Best estimate of 60 × 12? (a) 60 (b) 6000 (c) 600
  7. 7.Best estimate of 501 + 275? (a) 1000 (b) 800 (c) 600
  8. 8.Best estimate of 12 × 16? (a) 2000 (b) 200 (c) 20
  9. 9.Best estimate of 54 × 21? (a) 10000 (b) 1000 (c) 100
  10. 10.Best estimate of 443 + 145? (a) 300 (b) 700 (c) 500
  11. 11.Best estimate of 755 + 713? (a) 1700 (b) 1500 (c) 1300
  12. 12.Best estimate of 432 + 291? (a) 700 (b) 500 (c) 900
  13. 13.Best estimate of 16 × 18? (a) 400 (b) 4000 (c) 40
  14. 14.Best estimate of 397 + 303? (a) 700 (b) 500 (c) 900
  15. 15.Best estimate of 39 × 40? (a) 160 (b) 16000 (c) 1600
  16. 16.Best estimate of 73 × 18? (a) 14000 (b) 140 (c) 1400
  17. 17.Best estimate of 310 + 765? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 21 × 57? (a) 1200 (b) 120 (c) 12000
  19. 19.Best estimate of 38 × 28? (a) 1200 (b) 120 (c) 12000
  20. 20.Best estimate of 92 × 97? (a) 9000 (b) 90000 (c) 900
  21. 21.Best estimate of 123 + 696? (a) 800 (b) 1000 (c) 600
  22. 22.Best estimate of 54 × 27? (a) 15000 (b) 150 (c) 1500
  23. 23.Best estimate of 62 × 66? (a) 4200 (b) 420 (c) 42000
  24. 24.Best estimate of 528 + 245? (a) 900 (b) 700 (c) 500
  25. 25.Best estimate of 54 × 86? (a) 45000 (b) 450 (c) 4500
  26. 26.Best estimate of 659 + 441? (a) 900 (b) 1100 (c) 1300
  27. 27.Best estimate of 442 + 325? (a) 700 (b) 500 (c) 900
  28. 28.Best estimate of 32 × 76? (a) 240 (b) 2400 (c) 24000
  29. 29.Best estimate of 53 × 19? (a) 100 (b) 10000 (c) 1000
  30. 30.Best estimate of 839 + 358? (a) 1200 (b) 1000 (c) 1400
  31. 31.Best estimate of 609 + 308? (a) 700 (b) 1100 (c) 900
  32. 32.Best estimate of 30 × 54? (a) 150 (b) 1500 (c) 15000
  33. 33.Best estimate of 480 + 176? (a) 500 (b) 900 (c) 700
  34. 34.Best estimate of 29 × 28? (a) 900 (b) 9000 (c) 90
  35. 35.Best estimate of 547 + 690? (a) 1400 (b) 1200 (c) 1000
  36. 36.Best estimate of 870 + 578? (a) 1700 (b) 1500 (c) 1300
  37. 37.Best estimate of 52 × 89? (a) 45000 (b) 4500 (c) 450
  38. 38.Best estimate of 64 × 68? (a) 420 (b) 4200 (c) 42000
  39. 39.Best estimate of 459 + 570? (a) 1100 (b) 1300 (c) 900
  40. 40.Best estimate of 186 + 811? (a) 1200 (b) 800 (c) 1000

Answer key

  1. 900
  2. 3600
  3. 6300
  4. 2400
  5. 1400
  6. 600
  7. 800
  8. 200
  9. 1000
  10. 500
  11. 1500
  12. 700
  13. 400
  14. 700
  15. 1600
  16. 1400
  17. 1100
  18. 1200
  19. 1200
  20. 9000
  21. 800
  22. 1500
  23. 4200
  24. 700
  25. 4500
  26. 1100
  27. 700
  28. 2400
  29. 1000
  30. 1200
  31. 900
  32. 1500
  33. 700
  34. 900
  35. 1200
  36. 1500
  37. 4500
  38. 4200
  39. 1100
  40. 1000

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