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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 637 · 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 164 + 629? (a) 800 (b) 1000 (c) 600
  2. 2.Best estimate of 19 × 24? (a) 400 (b) 40 (c) 4000
  3. 3.Best estimate of 493 + 419? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 29 × 86? (a) 270 (b) 2700 (c) 27000
  5. 5.Best estimate of 80 × 50? (a) 4000 (b) 400 (c) 40000
  6. 6.Best estimate of 448 + 363? (a) 800 (b) 1000 (c) 600
  7. 7.Best estimate of 298 + 674? (a) 1000 (b) 1200 (c) 800
  8. 8.Best estimate of 13 × 87? (a) 90 (b) 9000 (c) 900
  9. 9.Best estimate of 129 + 427? (a) 300 (b) 700 (c) 500
  10. 10.Best estimate of 875 + 635? (a) 1700 (b) 1300 (c) 1500
  11. 11.Best estimate of 46 × 53? (a) 2500 (b) 250 (c) 25000
  12. 12.Best estimate of 332 + 139? (a) 200 (b) 600 (c) 400
  13. 13.Best estimate of 703 + 345? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 695 + 191? (a) 700 (b) 900 (c) 1100
  15. 15.Best estimate of 770 + 210? (a) 1000 (b) 800 (c) 1200
  16. 16.Best estimate of 30 × 52? (a) 15000 (b) 150 (c) 1500
  17. 17.Best estimate of 36 × 80? (a) 320 (b) 32000 (c) 3200
  18. 18.Best estimate of 78 × 46? (a) 4000 (b) 40000 (c) 400
  19. 19.Best estimate of 21 × 97? (a) 20000 (b) 2000 (c) 200
  20. 20.Best estimate of 205 + 462? (a) 900 (b) 500 (c) 700
  21. 21.Best estimate of 50 × 74? (a) 350 (b) 35000 (c) 3500
  22. 22.Best estimate of 73 × 77? (a) 56000 (b) 5600 (c) 560
  23. 23.Best estimate of 60 × 82? (a) 4800 (b) 48000 (c) 480
  24. 24.Best estimate of 134 + 346? (a) 400 (b) 600 (c) 200
  25. 25.Best estimate of 81 × 84? (a) 64000 (b) 640 (c) 6400
  26. 26.Best estimate of 76 × 91? (a) 7200 (b) 72000 (c) 720
  27. 27.Best estimate of 272 + 470? (a) 1000 (b) 800 (c) 600
  28. 28.Best estimate of 46 × 33? (a) 150 (b) 1500 (c) 15000
  29. 29.Best estimate of 377 + 493? (a) 700 (b) 1100 (c) 900
  30. 30.Best estimate of 66 × 16? (a) 1400 (b) 14000 (c) 140
  31. 31.Best estimate of 286 + 696? (a) 1000 (b) 800 (c) 1200
  32. 32.Best estimate of 189 + 562? (a) 1000 (b) 800 (c) 600
  33. 33.Best estimate of 90 × 54? (a) 45000 (b) 450 (c) 4500
  34. 34.Best estimate of 30 × 36? (a) 120 (b) 12000 (c) 1200
  35. 35.Best estimate of 46 × 18? (a) 100 (b) 10000 (c) 1000
  36. 36.Best estimate of 135 + 879? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 93 × 72? (a) 630 (b) 6300 (c) 63000
  38. 38.Best estimate of 472 + 254? (a) 800 (b) 600 (c) 1000
  39. 39.Best estimate of 58 × 19? (a) 1200 (b) 120 (c) 12000
  40. 40.Best estimate of 353 + 626? (a) 1200 (b) 1000 (c) 800

Answer key

  1. 800
  2. 400
  3. 900
  4. 2700
  5. 4000
  6. 800
  7. 1000
  8. 900
  9. 500
  10. 1500
  11. 2500
  12. 400
  13. 1000
  14. 900
  15. 1000
  16. 1500
  17. 3200
  18. 4000
  19. 2000
  20. 700
  21. 3500
  22. 5600
  23. 4800
  24. 400
  25. 6400
  26. 7200
  27. 800
  28. 1500
  29. 900
  30. 1400
  31. 1000
  32. 800
  33. 4500
  34. 1200
  35. 1000
  36. 1000
  37. 6300
  38. 800
  39. 1200
  40. 1000

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