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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 604 · 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 47 × 13? (a) 500 (b) 5000 (c) 50
  2. 2.Best estimate of 97 × 69? (a) 700 (b) 70000 (c) 7000
  3. 3.Best estimate of 152 + 759? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 720 + 555? (a) 1500 (b) 1300 (c) 1100
  5. 5.Best estimate of 188 + 165? (a) 600 (b) 200 (c) 400
  6. 6.Best estimate of 58 × 66? (a) 42000 (b) 4200 (c) 420
  7. 7.Best estimate of 74 × 43? (a) 2800 (b) 280 (c) 28000
  8. 8.Best estimate of 81 × 90? (a) 72000 (b) 7200 (c) 720
  9. 9.Best estimate of 690 + 380? (a) 900 (b) 1100 (c) 1300
  10. 10.Best estimate of 681 + 877? (a) 1400 (b) 1800 (c) 1600
  11. 11.Best estimate of 49 × 38? (a) 2000 (b) 20000 (c) 200
  12. 12.Best estimate of 169 + 839? (a) 1000 (b) 800 (c) 1200
  13. 13.Best estimate of 70 × 18? (a) 14000 (b) 1400 (c) 140
  14. 14.Best estimate of 463 + 705? (a) 1000 (b) 1200 (c) 1400
  15. 15.Best estimate of 53 × 30? (a) 1500 (b) 150 (c) 15000
  16. 16.Best estimate of 860 + 279? (a) 1200 (b) 1400 (c) 1000
  17. 17.Best estimate of 44 × 18? (a) 800 (b) 80 (c) 8000
  18. 18.Best estimate of 262 + 678? (a) 800 (b) 1200 (c) 1000
  19. 19.Best estimate of 335 + 178? (a) 500 (b) 700 (c) 300
  20. 20.Best estimate of 21 × 28? (a) 60 (b) 600 (c) 6000
  21. 21.Best estimate of 86 × 36? (a) 3600 (b) 36000 (c) 360
  22. 22.Best estimate of 86 × 61? (a) 540 (b) 5400 (c) 54000
  23. 23.Best estimate of 72 × 36? (a) 28000 (b) 280 (c) 2800
  24. 24.Best estimate of 230 + 386? (a) 600 (b) 400 (c) 800
  25. 25.Best estimate of 30 × 16? (a) 6000 (b) 600 (c) 60
  26. 26.Best estimate of 419 + 297? (a) 500 (b) 700 (c) 900
  27. 27.Best estimate of 37 × 28? (a) 1200 (b) 120 (c) 12000
  28. 28.Best estimate of 14 × 18? (a) 200 (b) 2000 (c) 20
  29. 29.Best estimate of 176 + 372? (a) 800 (b) 400 (c) 600
  30. 30.Best estimate of 787 + 516? (a) 1500 (b) 1300 (c) 1100
  31. 31.Best estimate of 751 + 262? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 31 × 17? (a) 600 (b) 60 (c) 6000
  33. 33.Best estimate of 194 + 346? (a) 500 (b) 300 (c) 700
  34. 34.Best estimate of 428 + 490? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 303 + 739? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 436 + 713? (a) 1100 (b) 900 (c) 1300
  37. 37.Best estimate of 482 + 212? (a) 700 (b) 500 (c) 900
  38. 38.Best estimate of 463 + 233? (a) 500 (b) 700 (c) 900
  39. 39.Best estimate of 171 + 824? (a) 1000 (b) 800 (c) 1200
  40. 40.Best estimate of 767 + 670? (a) 1500 (b) 1700 (c) 1300

Answer key

  1. 500
  2. 7000
  3. 1000
  4. 1300
  5. 400
  6. 4200
  7. 2800
  8. 7200
  9. 1100
  10. 1600
  11. 2000
  12. 1000
  13. 1400
  14. 1200
  15. 1500
  16. 1200
  17. 800
  18. 1000
  19. 500
  20. 600
  21. 3600
  22. 5400
  23. 2800
  24. 600
  25. 600
  26. 700
  27. 1200
  28. 200
  29. 600
  30. 1300
  31. 1100
  32. 600
  33. 500
  34. 900
  35. 1000
  36. 1100
  37. 700
  38. 700
  39. 1000
  40. 1500

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