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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 799 · 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 92 × 32? (a) 27000 (b) 2700 (c) 270
  2. 2.Best estimate of 30 × 14? (a) 3000 (b) 30 (c) 300
  3. 3.Best estimate of 703 + 221? (a) 1100 (b) 700 (c) 900
  4. 4.Best estimate of 769 + 793? (a) 1600 (b) 1400 (c) 1800
  5. 5.Best estimate of 82 × 40? (a) 32000 (b) 3200 (c) 320
  6. 6.Best estimate of 864 + 205? (a) 900 (b) 1100 (c) 1300
  7. 7.Best estimate of 43 × 21? (a) 8000 (b) 800 (c) 80
  8. 8.Best estimate of 53 × 74? (a) 3500 (b) 35000 (c) 350
  9. 9.Best estimate of 385 + 573? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 34 × 18? (a) 60 (b) 6000 (c) 600
  11. 11.Best estimate of 27 × 96? (a) 300 (b) 3000 (c) 30000
  12. 12.Best estimate of 87 × 73? (a) 6300 (b) 63000 (c) 630
  13. 13.Best estimate of 27 × 33? (a) 9000 (b) 90 (c) 900
  14. 14.Best estimate of 48 × 63? (a) 30000 (b) 300 (c) 3000
  15. 15.Best estimate of 14 × 80? (a) 80 (b) 800 (c) 8000
  16. 16.Best estimate of 382 + 393? (a) 800 (b) 1000 (c) 600
  17. 17.Best estimate of 23 × 24? (a) 4000 (b) 40 (c) 400
  18. 18.Best estimate of 86 × 69? (a) 63000 (b) 6300 (c) 630
  19. 19.Best estimate of 255 + 497? (a) 1000 (b) 800 (c) 600
  20. 20.Best estimate of 874 + 301? (a) 1400 (b) 1000 (c) 1200
  21. 21.Best estimate of 141 + 566? (a) 500 (b) 700 (c) 900
  22. 22.Best estimate of 207 + 402? (a) 400 (b) 800 (c) 600
  23. 23.Best estimate of 52 × 58? (a) 3000 (b) 30000 (c) 300
  24. 24.Best estimate of 31 × 79? (a) 2400 (b) 24000 (c) 240
  25. 25.Best estimate of 627 + 811? (a) 1600 (b) 1400 (c) 1200
  26. 26.Best estimate of 847 + 294? (a) 1300 (b) 1100 (c) 900
  27. 27.Best estimate of 464 + 409? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 300 + 176? (a) 500 (b) 700 (c) 300
  29. 29.Best estimate of 60 × 43? (a) 2400 (b) 24000 (c) 240
  30. 30.Best estimate of 53 × 46? (a) 2500 (b) 250 (c) 25000
  31. 31.Best estimate of 31 × 80? (a) 2400 (b) 24000 (c) 240
  32. 32.Best estimate of 30 × 93? (a) 270 (b) 2700 (c) 27000
  33. 33.Best estimate of 34 × 39? (a) 120 (b) 12000 (c) 1200
  34. 34.Best estimate of 63 × 68? (a) 420 (b) 4200 (c) 42000
  35. 35.Best estimate of 84 × 38? (a) 3200 (b) 320 (c) 32000
  36. 36.Best estimate of 262 + 136? (a) 400 (b) 200 (c) 600
  37. 37.Best estimate of 328 + 445? (a) 500 (b) 700 (c) 900
  38. 38.Best estimate of 62 × 16? (a) 1200 (b) 120 (c) 12000
  39. 39.Best estimate of 19 × 14? (a) 200 (b) 2000 (c) 20
  40. 40.Best estimate of 81 × 94? (a) 72000 (b) 720 (c) 7200

Answer key

  1. 2700
  2. 300
  3. 900
  4. 1600
  5. 3200
  6. 1100
  7. 800
  8. 3500
  9. 1000
  10. 600
  11. 3000
  12. 6300
  13. 900
  14. 3000
  15. 800
  16. 800
  17. 400
  18. 6300
  19. 800
  20. 1200
  21. 700
  22. 600
  23. 3000
  24. 2400
  25. 1400
  26. 1100
  27. 900
  28. 500
  29. 2400
  30. 2500
  31. 2400
  32. 2700
  33. 1200
  34. 4200
  35. 3200
  36. 400
  37. 700
  38. 1200
  39. 200
  40. 7200

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