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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 765 · 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 818 + 447? (a) 1000 (b) 1200 (c) 1400
  2. 2.Best estimate of 78 × 23? (a) 1600 (b) 160 (c) 16000
  3. 3.Best estimate of 469 + 828? (a) 1100 (b) 1500 (c) 1300
  4. 4.Best estimate of 51 × 38? (a) 20000 (b) 200 (c) 2000
  5. 5.Best estimate of 422 + 610? (a) 1000 (b) 800 (c) 1200
  6. 6.Best estimate of 742 + 485? (a) 1400 (b) 1000 (c) 1200
  7. 7.Best estimate of 578 + 571? (a) 1000 (b) 1200 (c) 1400
  8. 8.Best estimate of 44 × 33? (a) 1200 (b) 120 (c) 12000
  9. 9.Best estimate of 97 × 52? (a) 50000 (b) 5000 (c) 500
  10. 10.Best estimate of 684 + 331? (a) 1200 (b) 800 (c) 1000
  11. 11.Best estimate of 53 × 88? (a) 45000 (b) 4500 (c) 450
  12. 12.Best estimate of 26 × 43? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 177 + 279? (a) 300 (b) 700 (c) 500
  14. 14.Best estimate of 70 × 98? (a) 700 (b) 70000 (c) 7000
  15. 15.Best estimate of 52 × 72? (a) 3500 (b) 350 (c) 35000
  16. 16.Best estimate of 286 + 551? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 537 + 314? (a) 800 (b) 600 (c) 1000
  18. 18.Best estimate of 38 × 77? (a) 3200 (b) 32000 (c) 320
  19. 19.Best estimate of 153 + 368? (a) 800 (b) 600 (c) 400
  20. 20.Best estimate of 690 + 483? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 139 + 228? (a) 300 (b) 100 (c) 500
  22. 22.Best estimate of 54 × 61? (a) 30000 (b) 300 (c) 3000
  23. 23.Best estimate of 23 × 14? (a) 200 (b) 20 (c) 2000
  24. 24.Best estimate of 213 + 725? (a) 1100 (b) 700 (c) 900
  25. 25.Best estimate of 806 + 538? (a) 1300 (b) 1500 (c) 1100
  26. 26.Best estimate of 19 × 36? (a) 800 (b) 80 (c) 8000
  27. 27.Best estimate of 36 × 72? (a) 28000 (b) 280 (c) 2800
  28. 28.Best estimate of 66 × 97? (a) 70000 (b) 7000 (c) 700
  29. 29.Best estimate of 34 × 26? (a) 9000 (b) 90 (c) 900
  30. 30.Best estimate of 21 × 83? (a) 16000 (b) 160 (c) 1600
  31. 31.Best estimate of 162 + 221? (a) 400 (b) 600 (c) 200
  32. 32.Best estimate of 818 + 508? (a) 1100 (b) 1300 (c) 1500
  33. 33.Best estimate of 71 × 53? (a) 3500 (b) 35000 (c) 350
  34. 34.Best estimate of 318 + 773? (a) 1300 (b) 1100 (c) 900
  35. 35.Best estimate of 23 × 87? (a) 180 (b) 18000 (c) 1800
  36. 36.Best estimate of 89 × 47? (a) 45000 (b) 450 (c) 4500
  37. 37.Best estimate of 338 + 746? (a) 1200 (b) 800 (c) 1000
  38. 38.Best estimate of 72 × 87? (a) 63000 (b) 6300 (c) 630
  39. 39.Best estimate of 222 + 151? (a) 400 (b) 200 (c) 600
  40. 40.Best estimate of 96 × 53? (a) 5000 (b) 500 (c) 50000

Answer key

  1. 1200
  2. 1600
  3. 1300
  4. 2000
  5. 1000
  6. 1200
  7. 1200
  8. 1200
  9. 5000
  10. 1000
  11. 4500
  12. 1200
  13. 500
  14. 7000
  15. 3500
  16. 900
  17. 800
  18. 3200
  19. 600
  20. 1200
  21. 300
  22. 3000
  23. 200
  24. 900
  25. 1300
  26. 800
  27. 2800
  28. 7000
  29. 900
  30. 1600
  31. 400
  32. 1300
  33. 3500
  34. 1100
  35. 1800
  36. 4500
  37. 1000
  38. 6300
  39. 400
  40. 5000

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