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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 582 · 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 81 × 19? (a) 160 (b) 16000 (c) 1600
  2. 2.Best estimate of 50 × 96? (a) 500 (b) 5000 (c) 50000
  3. 3.Best estimate of 89 × 96? (a) 90000 (b) 900 (c) 9000
  4. 4.Best estimate of 211 + 704? (a) 700 (b) 1100 (c) 900
  5. 5.Best estimate of 76 × 64? (a) 4800 (b) 480 (c) 48000
  6. 6.Best estimate of 47 × 86? (a) 4500 (b) 45000 (c) 450
  7. 7.Best estimate of 50 × 22? (a) 100 (b) 10000 (c) 1000
  8. 8.Best estimate of 56 × 68? (a) 4200 (b) 420 (c) 42000
  9. 9.Best estimate of 63 × 58? (a) 36000 (b) 3600 (c) 360
  10. 10.Best estimate of 665 + 817? (a) 1500 (b) 1700 (c) 1300
  11. 11.Best estimate of 27 × 72? (a) 2100 (b) 21000 (c) 210
  12. 12.Best estimate of 86 × 26? (a) 27000 (b) 2700 (c) 270
  13. 13.Best estimate of 640 + 788? (a) 1400 (b) 1600 (c) 1200
  14. 14.Best estimate of 66 × 16? (a) 140 (b) 1400 (c) 14000
  15. 15.Best estimate of 23 × 44? (a) 80 (b) 8000 (c) 800
  16. 16.Best estimate of 71 × 93? (a) 630 (b) 6300 (c) 63000
  17. 17.Best estimate of 426 + 185? (a) 400 (b) 800 (c) 600
  18. 18.Best estimate of 259 + 142? (a) 200 (b) 400 (c) 600
  19. 19.Best estimate of 70 × 49? (a) 350 (b) 3500 (c) 35000
  20. 20.Best estimate of 337 + 412? (a) 500 (b) 700 (c) 900
  21. 21.Best estimate of 607 + 608? (a) 1000 (b) 1400 (c) 1200
  22. 22.Best estimate of 318 + 312? (a) 800 (b) 600 (c) 400
  23. 23.Best estimate of 272 + 307? (a) 400 (b) 600 (c) 800
  24. 24.Best estimate of 814 + 743? (a) 1500 (b) 1300 (c) 1700
  25. 25.Best estimate of 576 + 545? (a) 900 (b) 1300 (c) 1100
  26. 26.Best estimate of 82 × 14? (a) 800 (b) 80 (c) 8000
  27. 27.Best estimate of 598 + 180? (a) 1000 (b) 800 (c) 600
  28. 28.Best estimate of 86 × 12? (a) 9000 (b) 90 (c) 900
  29. 29.Best estimate of 83 × 44? (a) 320 (b) 3200 (c) 32000
  30. 30.Best estimate of 46 × 19? (a) 100 (b) 10000 (c) 1000
  31. 31.Best estimate of 776 + 444? (a) 1000 (b) 1200 (c) 1400
  32. 32.Best estimate of 418 + 653? (a) 1100 (b) 900 (c) 1300
  33. 33.Best estimate of 570 + 589? (a) 1000 (b) 1200 (c) 1400
  34. 34.Best estimate of 92 × 70? (a) 63000 (b) 6300 (c) 630
  35. 35.Best estimate of 220 + 332? (a) 500 (b) 700 (c) 300
  36. 36.Best estimate of 48 × 34? (a) 15000 (b) 1500 (c) 150
  37. 37.Best estimate of 34 × 83? (a) 2400 (b) 240 (c) 24000
  38. 38.Best estimate of 77 × 74? (a) 5600 (b) 560 (c) 56000
  39. 39.Best estimate of 12 × 33? (a) 30 (b) 3000 (c) 300
  40. 40.Best estimate of 312 + 610? (a) 900 (b) 1100 (c) 700

Answer key

  1. 1600
  2. 5000
  3. 9000
  4. 900
  5. 4800
  6. 4500
  7. 1000
  8. 4200
  9. 3600
  10. 1500
  11. 2100
  12. 2700
  13. 1400
  14. 1400
  15. 800
  16. 6300
  17. 600
  18. 400
  19. 3500
  20. 700
  21. 1200
  22. 600
  23. 600
  24. 1500
  25. 1100
  26. 800
  27. 800
  28. 900
  29. 3200
  30. 1000
  31. 1200
  32. 1100
  33. 1200
  34. 6300
  35. 500
  36. 1500
  37. 2400
  38. 5600
  39. 300
  40. 900

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