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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 217 · 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 36 × 38? (a) 160 (b) 1600 (c) 16000
  2. 2.Best estimate of 46 × 43? (a) 20000 (b) 200 (c) 2000
  3. 3.Best estimate of 84 × 36? (a) 32000 (b) 3200 (c) 320
  4. 4.Best estimate of 545 + 808? (a) 1300 (b) 1500 (c) 1100
  5. 5.Best estimate of 76 × 16? (a) 1600 (b) 16000 (c) 160
  6. 6.Best estimate of 29 × 46? (a) 1500 (b) 150 (c) 15000
  7. 7.Best estimate of 73 × 51? (a) 35000 (b) 350 (c) 3500
  8. 8.Best estimate of 36 × 47? (a) 2000 (b) 200 (c) 20000
  9. 9.Best estimate of 262 + 223? (a) 700 (b) 500 (c) 300
  10. 10.Best estimate of 166 + 196? (a) 600 (b) 200 (c) 400
  11. 11.Best estimate of 21 × 22? (a) 400 (b) 4000 (c) 40
  12. 12.Best estimate of 137 + 163? (a) 100 (b) 300 (c) 500
  13. 13.Best estimate of 38 × 98? (a) 400 (b) 4000 (c) 40000
  14. 14.Best estimate of 258 + 594? (a) 1100 (b) 900 (c) 700
  15. 15.Best estimate of 751 + 264? (a) 900 (b) 1100 (c) 1300
  16. 16.Best estimate of 545 + 423? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 31 × 40? (a) 120 (b) 1200 (c) 12000
  18. 18.Best estimate of 216 + 668? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 16 × 20? (a) 40 (b) 4000 (c) 400
  20. 20.Best estimate of 13 × 79? (a) 8000 (b) 800 (c) 80
  21. 21.Best estimate of 26 × 82? (a) 24000 (b) 240 (c) 2400
  22. 22.Best estimate of 76 × 19? (a) 1600 (b) 16000 (c) 160
  23. 23.Best estimate of 799 + 293? (a) 1300 (b) 900 (c) 1100
  24. 24.Best estimate of 624 + 510? (a) 1300 (b) 1100 (c) 900
  25. 25.Best estimate of 33 × 80? (a) 24000 (b) 2400 (c) 240
  26. 26.Best estimate of 22 × 46? (a) 100 (b) 10000 (c) 1000
  27. 27.Best estimate of 537 + 621? (a) 900 (b) 1300 (c) 1100
  28. 28.Best estimate of 71 × 61? (a) 4200 (b) 42000 (c) 420
  29. 29.Best estimate of 257 + 270? (a) 800 (b) 600 (c) 400
  30. 30.Best estimate of 34 × 50? (a) 15000 (b) 1500 (c) 150
  31. 31.Best estimate of 249 + 527? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 269 + 341? (a) 800 (b) 600 (c) 400
  33. 33.Best estimate of 50 × 68? (a) 35000 (b) 3500 (c) 350
  34. 34.Best estimate of 272 + 814? (a) 900 (b) 1100 (c) 1300
  35. 35.Best estimate of 292 + 695? (a) 800 (b) 1000 (c) 1200
  36. 36.Best estimate of 32 × 24? (a) 600 (b) 60 (c) 6000
  37. 37.Best estimate of 14 × 48? (a) 5000 (b) 500 (c) 50
  38. 38.Best estimate of 74 × 63? (a) 42000 (b) 4200 (c) 420
  39. 39.Best estimate of 310 + 474? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 39 × 40? (a) 160 (b) 16000 (c) 1600

Answer key

  1. 1600
  2. 2000
  3. 3200
  4. 1300
  5. 1600
  6. 1500
  7. 3500
  8. 2000
  9. 500
  10. 400
  11. 400
  12. 300
  13. 4000
  14. 900
  15. 1100
  16. 900
  17. 1200
  18. 900
  19. 400
  20. 800
  21. 2400
  22. 1600
  23. 1100
  24. 1100
  25. 2400
  26. 1000
  27. 1100
  28. 4200
  29. 600
  30. 1500
  31. 700
  32. 600
  33. 3500
  34. 1100
  35. 1000
  36. 600
  37. 500
  38. 4200
  39. 800
  40. 1600

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