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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 500 · 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 42 × 16? (a) 80 (b) 800 (c) 8000
  2. 2.Best estimate of 51 × 27? (a) 150 (b) 15000 (c) 1500
  3. 3.Best estimate of 88 × 53? (a) 45000 (b) 450 (c) 4500
  4. 4.Best estimate of 740 + 670? (a) 1600 (b) 1200 (c) 1400
  5. 5.Best estimate of 84 × 59? (a) 4800 (b) 48000 (c) 480
  6. 6.Best estimate of 151 + 588? (a) 600 (b) 1000 (c) 800
  7. 7.Best estimate of 58 × 18? (a) 1200 (b) 120 (c) 12000
  8. 8.Best estimate of 34 × 17? (a) 60 (b) 6000 (c) 600
  9. 9.Best estimate of 278 + 198? (a) 700 (b) 500 (c) 300
  10. 10.Best estimate of 147 + 319? (a) 200 (b) 600 (c) 400
  11. 11.Best estimate of 594 + 432? (a) 800 (b) 1200 (c) 1000
  12. 12.Best estimate of 249 + 248? (a) 200 (b) 600 (c) 400
  13. 13.Best estimate of 877 + 164? (a) 900 (b) 1300 (c) 1100
  14. 14.Best estimate of 68 × 40? (a) 2800 (b) 28000 (c) 280
  15. 15.Best estimate of 697 + 315? (a) 1200 (b) 1000 (c) 800
  16. 16.Best estimate of 16 × 72? (a) 14000 (b) 140 (c) 1400
  17. 17.Best estimate of 14 × 58? (a) 6000 (b) 60 (c) 600
  18. 18.Best estimate of 303 + 251? (a) 600 (b) 800 (c) 400
  19. 19.Best estimate of 36 × 82? (a) 3200 (b) 32000 (c) 320
  20. 20.Best estimate of 694 + 808? (a) 1700 (b) 1300 (c) 1500
  21. 21.Best estimate of 68 × 33? (a) 210 (b) 21000 (c) 2100
  22. 22.Best estimate of 131 + 315? (a) 600 (b) 400 (c) 200
  23. 23.Best estimate of 64 × 16? (a) 120 (b) 1200 (c) 12000
  24. 24.Best estimate of 26 × 84? (a) 2400 (b) 240 (c) 24000
  25. 25.Best estimate of 57 × 31? (a) 18000 (b) 180 (c) 1800
  26. 26.Best estimate of 73 × 78? (a) 560 (b) 56000 (c) 5600
  27. 27.Best estimate of 573 + 158? (a) 600 (b) 1000 (c) 800
  28. 28.Best estimate of 28 × 91? (a) 27000 (b) 2700 (c) 270
  29. 29.Best estimate of 371 + 502? (a) 1100 (b) 900 (c) 700
  30. 30.Best estimate of 52 × 30? (a) 150 (b) 15000 (c) 1500
  31. 31.Best estimate of 329 + 251? (a) 400 (b) 800 (c) 600
  32. 32.Best estimate of 16 × 52? (a) 1000 (b) 100 (c) 10000
  33. 33.Best estimate of 28 × 70? (a) 21000 (b) 210 (c) 2100
  34. 34.Best estimate of 197 + 668? (a) 1100 (b) 700 (c) 900
  35. 35.Best estimate of 163 + 160? (a) 200 (b) 600 (c) 400
  36. 36.Best estimate of 33 × 16? (a) 6000 (b) 600 (c) 60
  37. 37.Best estimate of 769 + 444? (a) 1200 (b) 1400 (c) 1000
  38. 38.Best estimate of 60 × 26? (a) 1800 (b) 18000 (c) 180
  39. 39.Best estimate of 139 + 802? (a) 1100 (b) 700 (c) 900
  40. 40.Best estimate of 255 + 731? (a) 1200 (b) 800 (c) 1000

Answer key

  1. 800
  2. 1500
  3. 4500
  4. 1400
  5. 4800
  6. 800
  7. 1200
  8. 600
  9. 500
  10. 400
  11. 1000
  12. 400
  13. 1100
  14. 2800
  15. 1000
  16. 1400
  17. 600
  18. 600
  19. 3200
  20. 1500
  21. 2100
  22. 400
  23. 1200
  24. 2400
  25. 1800
  26. 5600
  27. 800
  28. 2700
  29. 900
  30. 1500
  31. 600
  32. 1000
  33. 2100
  34. 900
  35. 400
  36. 600
  37. 1200
  38. 1800
  39. 900
  40. 1000

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