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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 570 · 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 87 × 50? (a) 4500 (b) 45000 (c) 450
  2. 2.Best estimate of 96 × 39? (a) 4000 (b) 400 (c) 40000
  3. 3.Best estimate of 62 × 82? (a) 4800 (b) 480 (c) 48000
  4. 4.Best estimate of 565 + 280? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 36 × 36? (a) 160 (b) 16000 (c) 1600
  6. 6.Best estimate of 84 × 97? (a) 8000 (b) 80000 (c) 800
  7. 7.Best estimate of 51 × 70? (a) 350 (b) 35000 (c) 3500
  8. 8.Best estimate of 596 + 751? (a) 1200 (b) 1400 (c) 1600
  9. 9.Best estimate of 538 + 222? (a) 900 (b) 700 (c) 500
  10. 10.Best estimate of 765 + 723? (a) 1500 (b) 1700 (c) 1300
  11. 11.Best estimate of 86 × 22? (a) 180 (b) 1800 (c) 18000
  12. 12.Best estimate of 57 × 23? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 46 × 66? (a) 35000 (b) 350 (c) 3500
  14. 14.Best estimate of 89 × 72? (a) 63000 (b) 630 (c) 6300
  15. 15.Best estimate of 17 × 20? (a) 40 (b) 400 (c) 4000
  16. 16.Best estimate of 797 + 286? (a) 1100 (b) 900 (c) 1300
  17. 17.Best estimate of 156 + 233? (a) 400 (b) 600 (c) 200
  18. 18.Best estimate of 144 + 314? (a) 400 (b) 200 (c) 600
  19. 19.Best estimate of 163 + 192? (a) 600 (b) 400 (c) 200
  20. 20.Best estimate of 221 + 828? (a) 800 (b) 1000 (c) 1200
  21. 21.Best estimate of 404 + 251? (a) 500 (b) 700 (c) 900
  22. 22.Best estimate of 23 × 29? (a) 6000 (b) 600 (c) 60
  23. 23.Best estimate of 44 × 80? (a) 32000 (b) 3200 (c) 320
  24. 24.Best estimate of 449 + 410? (a) 800 (b) 1000 (c) 600
  25. 25.Best estimate of 517 + 164? (a) 900 (b) 500 (c) 700
  26. 26.Best estimate of 165 + 842? (a) 800 (b) 1200 (c) 1000
  27. 27.Best estimate of 668 + 773? (a) 1500 (b) 1300 (c) 1700
  28. 28.Best estimate of 26 × 19? (a) 600 (b) 60 (c) 6000
  29. 29.Best estimate of 63 × 57? (a) 36000 (b) 360 (c) 3600
  30. 30.Best estimate of 93 × 60? (a) 5400 (b) 54000 (c) 540
  31. 31.Best estimate of 19 × 98? (a) 20000 (b) 2000 (c) 200
  32. 32.Best estimate of 473 + 303? (a) 1000 (b) 600 (c) 800
  33. 33.Best estimate of 211 + 137? (a) 100 (b) 300 (c) 500
  34. 34.Best estimate of 98 × 23? (a) 2000 (b) 20000 (c) 200
  35. 35.Best estimate of 78 × 52? (a) 4000 (b) 40000 (c) 400
  36. 36.Best estimate of 16 × 68? (a) 1400 (b) 140 (c) 14000
  37. 37.Best estimate of 309 + 441? (a) 700 (b) 500 (c) 900
  38. 38.Best estimate of 89 × 34? (a) 2700 (b) 270 (c) 27000
  39. 39.Best estimate of 14 × 22? (a) 2000 (b) 200 (c) 20
  40. 40.Best estimate of 738 + 765? (a) 1300 (b) 1700 (c) 1500

Answer key

  1. 4500
  2. 4000
  3. 4800
  4. 900
  5. 1600
  6. 8000
  7. 3500
  8. 1400
  9. 700
  10. 1500
  11. 1800
  12. 1200
  13. 3500
  14. 6300
  15. 400
  16. 1100
  17. 400
  18. 400
  19. 400
  20. 1000
  21. 700
  22. 600
  23. 3200
  24. 800
  25. 700
  26. 1000
  27. 1500
  28. 600
  29. 3600
  30. 5400
  31. 2000
  32. 800
  33. 300
  34. 2000
  35. 4000
  36. 1400
  37. 700
  38. 2700
  39. 200
  40. 1500

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