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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 812 · 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 26 × 88? (a) 270 (b) 27000 (c) 2700
  2. 2.Best estimate of 245 + 201? (a) 600 (b) 400 (c) 200
  3. 3.Best estimate of 84 × 96? (a) 80000 (b) 8000 (c) 800
  4. 4.Best estimate of 19 × 46? (a) 100 (b) 10000 (c) 1000
  5. 5.Best estimate of 290 + 397? (a) 900 (b) 700 (c) 500
  6. 6.Best estimate of 687 + 541? (a) 1400 (b) 1000 (c) 1200
  7. 7.Best estimate of 59 × 44? (a) 240 (b) 24000 (c) 2400
  8. 8.Best estimate of 91 × 56? (a) 5400 (b) 54000 (c) 540
  9. 9.Best estimate of 503 + 413? (a) 1100 (b) 700 (c) 900
  10. 10.Best estimate of 77 × 54? (a) 40000 (b) 400 (c) 4000
  11. 11.Best estimate of 500 + 868? (a) 1600 (b) 1400 (c) 1200
  12. 12.Best estimate of 62 × 41? (a) 2400 (b) 24000 (c) 240
  13. 13.Best estimate of 33 × 92? (a) 270 (b) 2700 (c) 27000
  14. 14.Best estimate of 509 + 718? (a) 1200 (b) 1400 (c) 1000
  15. 15.Best estimate of 92 × 51? (a) 450 (b) 4500 (c) 45000
  16. 16.Best estimate of 83 × 81? (a) 6400 (b) 64000 (c) 640
  17. 17.Best estimate of 549 + 709? (a) 1400 (b) 1000 (c) 1200
  18. 18.Best estimate of 59 × 31? (a) 18000 (b) 1800 (c) 180
  19. 19.Best estimate of 421 + 372? (a) 800 (b) 1000 (c) 600
  20. 20.Best estimate of 328 + 723? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 462 + 217? (a) 900 (b) 700 (c) 500
  22. 22.Best estimate of 637 + 374? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 378 + 531? (a) 700 (b) 1100 (c) 900
  24. 24.Best estimate of 235 + 314? (a) 500 (b) 700 (c) 300
  25. 25.Best estimate of 24 × 32? (a) 6000 (b) 60 (c) 600
  26. 26.Best estimate of 40 × 31? (a) 12000 (b) 120 (c) 1200
  27. 27.Best estimate of 34 × 38? (a) 120 (b) 1200 (c) 12000
  28. 28.Best estimate of 93 × 49? (a) 4500 (b) 45000 (c) 450
  29. 29.Best estimate of 676 + 173? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 465 + 390? (a) 900 (b) 1100 (c) 700
  31. 31.Best estimate of 26 × 42? (a) 1200 (b) 12000 (c) 120
  32. 32.Best estimate of 555 + 260? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 308 + 504? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 838 + 591? (a) 1400 (b) 1600 (c) 1200
  35. 35.Best estimate of 96 × 32? (a) 30000 (b) 3000 (c) 300
  36. 36.Best estimate of 48 × 91? (a) 450 (b) 45000 (c) 4500
  37. 37.Best estimate of 13 × 16? (a) 200 (b) 20 (c) 2000
  38. 38.Best estimate of 339 + 508? (a) 1000 (b) 800 (c) 600
  39. 39.Best estimate of 800 + 480? (a) 1500 (b) 1100 (c) 1300
  40. 40.Best estimate of 372 + 296? (a) 900 (b) 500 (c) 700

Answer key

  1. 2700
  2. 400
  3. 8000
  4. 1000
  5. 700
  6. 1200
  7. 2400
  8. 5400
  9. 900
  10. 4000
  11. 1400
  12. 2400
  13. 2700
  14. 1200
  15. 4500
  16. 6400
  17. 1200
  18. 1800
  19. 800
  20. 1000
  21. 700
  22. 1000
  23. 900
  24. 500
  25. 600
  26. 1200
  27. 1200
  28. 4500
  29. 900
  30. 900
  31. 1200
  32. 900
  33. 800
  34. 1400
  35. 3000
  36. 4500
  37. 200
  38. 800
  39. 1300
  40. 700

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