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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 59 · 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 405 + 196? (a) 800 (b) 600 (c) 400
  2. 2.Best estimate of 256 + 526? (a) 1000 (b) 800 (c) 600
  3. 3.Best estimate of 60 × 91? (a) 54000 (b) 5400 (c) 540
  4. 4.Best estimate of 66 × 73? (a) 490 (b) 4900 (c) 49000
  5. 5.Best estimate of 532 + 782? (a) 1300 (b) 1500 (c) 1100
  6. 6.Best estimate of 337 + 228? (a) 500 (b) 300 (c) 700
  7. 7.Best estimate of 78 × 84? (a) 640 (b) 6400 (c) 64000
  8. 8.Best estimate of 96 × 18? (a) 2000 (b) 200 (c) 20000
  9. 9.Best estimate of 56 × 41? (a) 240 (b) 24000 (c) 2400
  10. 10.Best estimate of 64 × 72? (a) 4200 (b) 42000 (c) 420
  11. 11.Best estimate of 16 × 33? (a) 60 (b) 600 (c) 6000
  12. 12.Best estimate of 71 × 97? (a) 70000 (b) 700 (c) 7000
  13. 13.Best estimate of 46 × 17? (a) 1000 (b) 100 (c) 10000
  14. 14.Best estimate of 497 + 734? (a) 1000 (b) 1200 (c) 1400
  15. 15.Best estimate of 56 × 53? (a) 30000 (b) 3000 (c) 300
  16. 16.Best estimate of 773 + 496? (a) 1500 (b) 1300 (c) 1100
  17. 17.Best estimate of 23 × 83? (a) 1600 (b) 16000 (c) 160
  18. 18.Best estimate of 552 + 662? (a) 1100 (b) 1500 (c) 1300
  19. 19.Best estimate of 649 + 678? (a) 1300 (b) 1500 (c) 1100
  20. 20.Best estimate of 479 + 863? (a) 1400 (b) 1600 (c) 1200
  21. 21.Best estimate of 50 × 36? (a) 200 (b) 20000 (c) 2000
  22. 22.Best estimate of 53 × 57? (a) 300 (b) 3000 (c) 30000
  23. 23.Best estimate of 90 × 46? (a) 45000 (b) 450 (c) 4500
  24. 24.Best estimate of 17 × 24? (a) 4000 (b) 40 (c) 400
  25. 25.Best estimate of 78 × 26? (a) 240 (b) 24000 (c) 2400
  26. 26.Best estimate of 41 × 43? (a) 160 (b) 16000 (c) 1600
  27. 27.Best estimate of 92 × 29? (a) 270 (b) 27000 (c) 2700
  28. 28.Best estimate of 56 × 69? (a) 4200 (b) 42000 (c) 420
  29. 29.Best estimate of 430 + 319? (a) 700 (b) 900 (c) 500
  30. 30.Best estimate of 12 × 37? (a) 400 (b) 40 (c) 4000
  31. 31.Best estimate of 845 + 564? (a) 1600 (b) 1200 (c) 1400
  32. 32.Best estimate of 90 × 89? (a) 81000 (b) 8100 (c) 810
  33. 33.Best estimate of 19 × 51? (a) 100 (b) 1000 (c) 10000
  34. 34.Best estimate of 194 + 476? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 18 × 22? (a) 4000 (b) 400 (c) 40
  36. 36.Best estimate of 76 × 72? (a) 560 (b) 56000 (c) 5600
  37. 37.Best estimate of 36 × 57? (a) 240 (b) 2400 (c) 24000
  38. 38.Best estimate of 592 + 503? (a) 1300 (b) 1100 (c) 900
  39. 39.Best estimate of 226 + 459? (a) 900 (b) 500 (c) 700
  40. 40.Best estimate of 528 + 708? (a) 1400 (b) 1200 (c) 1000

Answer key

  1. 600
  2. 800
  3. 5400
  4. 4900
  5. 1300
  6. 500
  7. 6400
  8. 2000
  9. 2400
  10. 4200
  11. 600
  12. 7000
  13. 1000
  14. 1200
  15. 3000
  16. 1300
  17. 1600
  18. 1300
  19. 1300
  20. 1400
  21. 2000
  22. 3000
  23. 4500
  24. 400
  25. 2400
  26. 1600
  27. 2700
  28. 4200
  29. 700
  30. 400
  31. 1400
  32. 8100
  33. 1000
  34. 700
  35. 400
  36. 5600
  37. 2400
  38. 1100
  39. 700
  40. 1200

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