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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 788 · 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 58 × 23? (a) 120 (b) 1200 (c) 12000
  2. 2.Best estimate of 66 × 36? (a) 280 (b) 28000 (c) 2800
  3. 3.Best estimate of 126 + 764? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 548 + 719? (a) 1200 (b) 1400 (c) 1000
  5. 5.Best estimate of 27 × 50? (a) 15000 (b) 150 (c) 1500
  6. 6.Best estimate of 70 × 47? (a) 350 (b) 3500 (c) 35000
  7. 7.Best estimate of 716 + 658? (a) 1400 (b) 1600 (c) 1200
  8. 8.Best estimate of 753 + 674? (a) 1700 (b) 1500 (c) 1300
  9. 9.Best estimate of 44 × 79? (a) 320 (b) 32000 (c) 3200
  10. 10.Best estimate of 210 + 255? (a) 700 (b) 500 (c) 300
  11. 11.Best estimate of 247 + 368? (a) 800 (b) 400 (c) 600
  12. 12.Best estimate of 252 + 297? (a) 400 (b) 800 (c) 600
  13. 13.Best estimate of 80 × 87? (a) 720 (b) 72000 (c) 7200
  14. 14.Best estimate of 715 + 823? (a) 1700 (b) 1300 (c) 1500
  15. 15.Best estimate of 26 × 52? (a) 15000 (b) 1500 (c) 150
  16. 16.Best estimate of 276 + 152? (a) 300 (b) 700 (c) 500
  17. 17.Best estimate of 705 + 666? (a) 1400 (b) 1600 (c) 1200
  18. 18.Best estimate of 665 + 318? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 297 + 433? (a) 900 (b) 700 (c) 500
  20. 20.Best estimate of 86 × 87? (a) 81000 (b) 810 (c) 8100
  21. 21.Best estimate of 262 + 618? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 24 × 14? (a) 200 (b) 2000 (c) 20
  23. 23.Best estimate of 28 × 86? (a) 27000 (b) 2700 (c) 270
  24. 24.Best estimate of 239 + 860? (a) 1100 (b) 900 (c) 1300
  25. 25.Best estimate of 23 × 26? (a) 600 (b) 60 (c) 6000
  26. 26.Best estimate of 26 × 20? (a) 60 (b) 600 (c) 6000
  27. 27.Best estimate of 136 + 529? (a) 400 (b) 800 (c) 600
  28. 28.Best estimate of 21 × 48? (a) 1000 (b) 10000 (c) 100
  29. 29.Best estimate of 746 + 198? (a) 900 (b) 700 (c) 1100
  30. 30.Best estimate of 715 + 606? (a) 1100 (b) 1500 (c) 1300
  31. 31.Best estimate of 19 × 14? (a) 200 (b) 2000 (c) 20
  32. 32.Best estimate of 30 × 58? (a) 1800 (b) 18000 (c) 180
  33. 33.Best estimate of 400 + 376? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 205 + 746? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 39 × 36? (a) 160 (b) 16000 (c) 1600
  36. 36.Best estimate of 62 × 16? (a) 120 (b) 12000 (c) 1200
  37. 37.Best estimate of 151 + 286? (a) 300 (b) 500 (c) 700
  38. 38.Best estimate of 23 × 42? (a) 800 (b) 80 (c) 8000
  39. 39.Best estimate of 34 × 19? (a) 60 (b) 6000 (c) 600
  40. 40.Best estimate of 290 + 739? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 1200
  2. 2800
  3. 900
  4. 1200
  5. 1500
  6. 3500
  7. 1400
  8. 1500
  9. 3200
  10. 500
  11. 600
  12. 600
  13. 7200
  14. 1500
  15. 1500
  16. 500
  17. 1400
  18. 1000
  19. 700
  20. 8100
  21. 900
  22. 200
  23. 2700
  24. 1100
  25. 600
  26. 600
  27. 600
  28. 1000
  29. 900
  30. 1300
  31. 200
  32. 1800
  33. 800
  34. 900
  35. 1600
  36. 1200
  37. 500
  38. 800
  39. 600
  40. 1000

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