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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 286 · 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 84 × 98? (a) 80000 (b) 800 (c) 8000
  2. 2.Best estimate of 393 + 601? (a) 1200 (b) 1000 (c) 800
  3. 3.Best estimate of 57 × 89? (a) 54000 (b) 5400 (c) 540
  4. 4.Best estimate of 195 + 589? (a) 600 (b) 800 (c) 1000
  5. 5.Best estimate of 62 × 36? (a) 240 (b) 24000 (c) 2400
  6. 6.Best estimate of 317 + 426? (a) 700 (b) 900 (c) 500
  7. 7.Best estimate of 97 × 76? (a) 800 (b) 80000 (c) 8000
  8. 8.Best estimate of 29 × 28? (a) 9000 (b) 90 (c) 900
  9. 9.Best estimate of 38 × 73? (a) 2800 (b) 28000 (c) 280
  10. 10.Best estimate of 570 + 278? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 87 × 68? (a) 6300 (b) 63000 (c) 630
  12. 12.Best estimate of 355 + 738? (a) 1100 (b) 900 (c) 1300
  13. 13.Best estimate of 91 × 96? (a) 90000 (b) 900 (c) 9000
  14. 14.Best estimate of 333 + 224? (a) 500 (b) 700 (c) 300
  15. 15.Best estimate of 815 + 353? (a) 1000 (b) 1200 (c) 1400
  16. 16.Best estimate of 761 + 564? (a) 1200 (b) 1600 (c) 1400
  17. 17.Best estimate of 730 + 515? (a) 1400 (b) 1000 (c) 1200
  18. 18.Best estimate of 96 × 36? (a) 400 (b) 40000 (c) 4000
  19. 19.Best estimate of 38 × 20? (a) 80 (b) 8000 (c) 800
  20. 20.Best estimate of 20 × 30? (a) 6000 (b) 60 (c) 600
  21. 21.Best estimate of 702 + 318? (a) 1200 (b) 800 (c) 1000
  22. 22.Best estimate of 23 × 26? (a) 600 (b) 6000 (c) 60
  23. 23.Best estimate of 195 + 618? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 38 × 33? (a) 120 (b) 12000 (c) 1200
  25. 25.Best estimate of 625 + 377? (a) 1200 (b) 800 (c) 1000
  26. 26.Best estimate of 47 × 42? (a) 2000 (b) 20000 (c) 200
  27. 27.Best estimate of 198 + 493? (a) 500 (b) 900 (c) 700
  28. 28.Best estimate of 56 × 57? (a) 3600 (b) 360 (c) 36000
  29. 29.Best estimate of 78 × 87? (a) 7200 (b) 720 (c) 72000
  30. 30.Best estimate of 257 + 180? (a) 500 (b) 700 (c) 300
  31. 31.Best estimate of 169 + 544? (a) 700 (b) 900 (c) 500
  32. 32.Best estimate of 98 × 97? (a) 100000 (b) 1000 (c) 10000
  33. 33.Best estimate of 344 + 194? (a) 300 (b) 700 (c) 500
  34. 34.Best estimate of 537 + 852? (a) 1600 (b) 1400 (c) 1200
  35. 35.Best estimate of 57 × 62? (a) 360 (b) 36000 (c) 3600
  36. 36.Best estimate of 92 × 89? (a) 810 (b) 81000 (c) 8100
  37. 37.Best estimate of 84 × 44? (a) 3200 (b) 32000 (c) 320
  38. 38.Best estimate of 81 × 49? (a) 40000 (b) 400 (c) 4000
  39. 39.Best estimate of 26 × 64? (a) 1800 (b) 18000 (c) 180
  40. 40.Best estimate of 692 + 325? (a) 1000 (b) 800 (c) 1200

Answer key

  1. 8000
  2. 1000
  3. 5400
  4. 800
  5. 2400
  6. 700
  7. 8000
  8. 900
  9. 2800
  10. 900
  11. 6300
  12. 1100
  13. 9000
  14. 500
  15. 1200
  16. 1400
  17. 1200
  18. 4000
  19. 800
  20. 600
  21. 1000
  22. 600
  23. 800
  24. 1200
  25. 1000
  26. 2000
  27. 700
  28. 3600
  29. 7200
  30. 500
  31. 700
  32. 10000
  33. 500
  34. 1400
  35. 3600
  36. 8100
  37. 3200
  38. 4000
  39. 1800
  40. 1000

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