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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 579 · 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 798 + 698? (a) 1300 (b) 1500 (c) 1700
  2. 2.Best estimate of 627 + 235? (a) 600 (b) 800 (c) 1000
  3. 3.Best estimate of 846 + 212? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 23 × 18? (a) 4000 (b) 40 (c) 400
  5. 5.Best estimate of 88 × 97? (a) 900 (b) 90000 (c) 9000
  6. 6.Best estimate of 697 + 530? (a) 1200 (b) 1400 (c) 1000
  7. 7.Best estimate of 210 + 525? (a) 700 (b) 500 (c) 900
  8. 8.Best estimate of 788 + 293? (a) 900 (b) 1100 (c) 1300
  9. 9.Best estimate of 758 + 768? (a) 1400 (b) 1600 (c) 1800
  10. 10.Best estimate of 827 + 331? (a) 900 (b) 1300 (c) 1100
  11. 11.Best estimate of 37 × 80? (a) 3200 (b) 32000 (c) 320
  12. 12.Best estimate of 503 + 272? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 262 + 365? (a) 900 (b) 700 (c) 500
  14. 14.Best estimate of 16 × 88? (a) 18000 (b) 1800 (c) 180
  15. 15.Best estimate of 61 × 20? (a) 1200 (b) 120 (c) 12000
  16. 16.Best estimate of 30 × 86? (a) 27000 (b) 2700 (c) 270
  17. 17.Best estimate of 84 × 14? (a) 8000 (b) 80 (c) 800
  18. 18.Best estimate of 36 × 74? (a) 2800 (b) 28000 (c) 280
  19. 19.Best estimate of 228 + 729? (a) 1100 (b) 900 (c) 700
  20. 20.Best estimate of 84 × 16? (a) 16000 (b) 160 (c) 1600
  21. 21.Best estimate of 41 × 17? (a) 800 (b) 80 (c) 8000
  22. 22.Best estimate of 60 × 93? (a) 5400 (b) 54000 (c) 540
  23. 23.Best estimate of 279 + 702? (a) 1000 (b) 1200 (c) 800
  24. 24.Best estimate of 28 × 34? (a) 9000 (b) 900 (c) 90
  25. 25.Best estimate of 775 + 613? (a) 1400 (b) 1600 (c) 1200
  26. 26.Best estimate of 491 + 379? (a) 900 (b) 700 (c) 1100
  27. 27.Best estimate of 53 × 69? (a) 3500 (b) 35000 (c) 350
  28. 28.Best estimate of 33 × 17? (a) 6000 (b) 60 (c) 600
  29. 29.Best estimate of 76 × 78? (a) 64000 (b) 640 (c) 6400
  30. 30.Best estimate of 72 × 60? (a) 420 (b) 42000 (c) 4200
  31. 31.Best estimate of 277 + 670? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 880 + 174? (a) 1300 (b) 1100 (c) 900
  33. 33.Best estimate of 33 × 27? (a) 900 (b) 90 (c) 9000
  34. 34.Best estimate of 816 + 243? (a) 1200 (b) 1000 (c) 800
  35. 35.Best estimate of 98 × 41? (a) 400 (b) 4000 (c) 40000
  36. 36.Best estimate of 18 × 36? (a) 8000 (b) 800 (c) 80
  37. 37.Best estimate of 29 × 42? (a) 1200 (b) 120 (c) 12000
  38. 38.Best estimate of 154 + 415? (a) 400 (b) 600 (c) 800
  39. 39.Best estimate of 34 × 76? (a) 24000 (b) 2400 (c) 240
  40. 40.Best estimate of 180 + 394? (a) 600 (b) 400 (c) 800

Answer key

  1. 1500
  2. 800
  3. 1000
  4. 400
  5. 9000
  6. 1200
  7. 700
  8. 1100
  9. 1600
  10. 1100
  11. 3200
  12. 800
  13. 700
  14. 1800
  15. 1200
  16. 2700
  17. 800
  18. 2800
  19. 900
  20. 1600
  21. 800
  22. 5400
  23. 1000
  24. 900
  25. 1400
  26. 900
  27. 3500
  28. 600
  29. 6400
  30. 4200
  31. 1000
  32. 1100
  33. 900
  34. 1000
  35. 4000
  36. 800
  37. 1200
  38. 600
  39. 2400
  40. 600

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