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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 468 · 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 33 × 70? (a) 21000 (b) 210 (c) 2100
  2. 2.Best estimate of 742 + 319? (a) 800 (b) 1000 (c) 1200
  3. 3.Best estimate of 423 + 295? (a) 500 (b) 900 (c) 700
  4. 4.Best estimate of 89 × 50? (a) 4500 (b) 450 (c) 45000
  5. 5.Best estimate of 96 × 16? (a) 2000 (b) 200 (c) 20000
  6. 6.Best estimate of 48 × 27? (a) 1500 (b) 150 (c) 15000
  7. 7.Best estimate of 601 + 217? (a) 800 (b) 1000 (c) 600
  8. 8.Best estimate of 401 + 830? (a) 1400 (b) 1000 (c) 1200
  9. 9.Best estimate of 89 × 63? (a) 54000 (b) 5400 (c) 540
  10. 10.Best estimate of 738 + 159? (a) 700 (b) 1100 (c) 900
  11. 11.Best estimate of 419 + 858? (a) 1100 (b) 1500 (c) 1300
  12. 12.Best estimate of 822 + 191? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 46 × 44? (a) 2000 (b) 20000 (c) 200
  14. 14.Best estimate of 28 × 43? (a) 120 (b) 12000 (c) 1200
  15. 15.Best estimate of 677 + 786? (a) 1300 (b) 1500 (c) 1700
  16. 16.Best estimate of 764 + 800? (a) 1800 (b) 1600 (c) 1400
  17. 17.Best estimate of 491 + 835? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 488 + 442? (a) 700 (b) 1100 (c) 900
  19. 19.Best estimate of 263 + 220? (a) 500 (b) 700 (c) 300
  20. 20.Best estimate of 90 × 28? (a) 27000 (b) 270 (c) 2700
  21. 21.Best estimate of 234 + 356? (a) 800 (b) 600 (c) 400
  22. 22.Best estimate of 486 + 849? (a) 1300 (b) 1500 (c) 1100
  23. 23.Best estimate of 36 × 71? (a) 28000 (b) 280 (c) 2800
  24. 24.Best estimate of 34 × 56? (a) 18000 (b) 1800 (c) 180
  25. 25.Best estimate of 96 × 19? (a) 20000 (b) 2000 (c) 200
  26. 26.Best estimate of 276 + 669? (a) 1200 (b) 800 (c) 1000
  27. 27.Best estimate of 86 × 16? (a) 1800 (b) 180 (c) 18000
  28. 28.Best estimate of 447 + 251? (a) 500 (b) 900 (c) 700
  29. 29.Best estimate of 56 × 20? (a) 12000 (b) 1200 (c) 120
  30. 30.Best estimate of 341 + 490? (a) 800 (b) 1000 (c) 600
  31. 31.Best estimate of 538 + 439? (a) 700 (b) 900 (c) 1100
  32. 32.Best estimate of 174 + 295? (a) 500 (b) 300 (c) 700
  33. 33.Best estimate of 12 × 72? (a) 700 (b) 70 (c) 7000
  34. 34.Best estimate of 813 + 586? (a) 1200 (b) 1400 (c) 1600
  35. 35.Best estimate of 758 + 156? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 66 × 84? (a) 560 (b) 56000 (c) 5600
  37. 37.Best estimate of 70 × 58? (a) 420 (b) 4200 (c) 42000
  38. 38.Best estimate of 23 × 69? (a) 14000 (b) 140 (c) 1400
  39. 39.Best estimate of 79 × 57? (a) 4800 (b) 480 (c) 48000
  40. 40.Best estimate of 76 × 92? (a) 72000 (b) 7200 (c) 720

Answer key

  1. 2100
  2. 1000
  3. 700
  4. 4500
  5. 2000
  6. 1500
  7. 800
  8. 1200
  9. 5400
  10. 900
  11. 1300
  12. 1000
  13. 2000
  14. 1200
  15. 1500
  16. 1600
  17. 1300
  18. 900
  19. 500
  20. 2700
  21. 600
  22. 1300
  23. 2800
  24. 1800
  25. 2000
  26. 1000
  27. 1800
  28. 700
  29. 1200
  30. 800
  31. 900
  32. 500
  33. 700
  34. 1400
  35. 1000
  36. 5600
  37. 4200
  38. 1400
  39. 4800
  40. 7200

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