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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 493 · 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 875 + 304? (a) 1000 (b) 1400 (c) 1200
  2. 2.Best estimate of 58 × 59? (a) 3600 (b) 36000 (c) 360
  3. 3.Best estimate of 52 × 36? (a) 200 (b) 2000 (c) 20000
  4. 4.Best estimate of 47 × 33? (a) 15000 (b) 1500 (c) 150
  5. 5.Best estimate of 77 × 59? (a) 4800 (b) 480 (c) 48000
  6. 6.Best estimate of 94 × 86? (a) 8100 (b) 810 (c) 81000
  7. 7.Best estimate of 46 × 44? (a) 200 (b) 2000 (c) 20000
  8. 8.Best estimate of 69 × 26? (a) 21000 (b) 2100 (c) 210
  9. 9.Best estimate of 87 × 97? (a) 9000 (b) 90000 (c) 900
  10. 10.Best estimate of 88 × 23? (a) 1800 (b) 180 (c) 18000
  11. 11.Best estimate of 64 × 60? (a) 360 (b) 3600 (c) 36000
  12. 12.Best estimate of 546 + 780? (a) 1100 (b) 1300 (c) 1500
  13. 13.Best estimate of 660 + 292? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 28 × 41? (a) 120 (b) 12000 (c) 1200
  15. 15.Best estimate of 548 + 283? (a) 1000 (b) 600 (c) 800
  16. 16.Best estimate of 610 + 208? (a) 800 (b) 600 (c) 1000
  17. 17.Best estimate of 495 + 337? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 34 × 79? (a) 2400 (b) 240 (c) 24000
  19. 19.Best estimate of 78 × 52? (a) 40000 (b) 400 (c) 4000
  20. 20.Best estimate of 320 + 603? (a) 700 (b) 1100 (c) 900
  21. 21.Best estimate of 48 × 16? (a) 100 (b) 10000 (c) 1000
  22. 22.Best estimate of 86 × 39? (a) 36000 (b) 3600 (c) 360
  23. 23.Best estimate of 198 + 686? (a) 900 (b) 1100 (c) 700
  24. 24.Best estimate of 217 + 425? (a) 800 (b) 600 (c) 400
  25. 25.Best estimate of 456 + 714? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 212 + 152? (a) 600 (b) 200 (c) 400
  27. 27.Best estimate of 91 × 40? (a) 36000 (b) 3600 (c) 360
  28. 28.Best estimate of 230 + 814? (a) 1000 (b) 800 (c) 1200
  29. 29.Best estimate of 397 + 808? (a) 1000 (b) 1400 (c) 1200
  30. 30.Best estimate of 76 × 97? (a) 80000 (b) 800 (c) 8000
  31. 31.Best estimate of 801 + 684? (a) 1300 (b) 1700 (c) 1500
  32. 32.Best estimate of 68 × 30? (a) 2100 (b) 21000 (c) 210
  33. 33.Best estimate of 79 × 88? (a) 7200 (b) 72000 (c) 720
  34. 34.Best estimate of 56 × 91? (a) 5400 (b) 540 (c) 54000
  35. 35.Best estimate of 31 × 20? (a) 6000 (b) 600 (c) 60
  36. 36.Best estimate of 219 + 379? (a) 800 (b) 600 (c) 400
  37. 37.Best estimate of 507 + 457? (a) 1000 (b) 1200 (c) 800
  38. 38.Best estimate of 364 + 173? (a) 600 (b) 400 (c) 800
  39. 39.Best estimate of 27 × 53? (a) 150 (b) 1500 (c) 15000
  40. 40.Best estimate of 506 + 552? (a) 1100 (b) 1300 (c) 900

Answer key

  1. 1200
  2. 3600
  3. 2000
  4. 1500
  5. 4800
  6. 8100
  7. 2000
  8. 2100
  9. 9000
  10. 1800
  11. 3600
  12. 1300
  13. 1000
  14. 1200
  15. 800
  16. 800
  17. 800
  18. 2400
  19. 4000
  20. 900
  21. 1000
  22. 3600
  23. 900
  24. 600
  25. 1200
  26. 400
  27. 3600
  28. 1000
  29. 1200
  30. 8000
  31. 1500
  32. 2100
  33. 7200
  34. 5400
  35. 600
  36. 600
  37. 1000
  38. 600
  39. 1500
  40. 1100

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