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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 642 · 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 211 + 351? (a) 600 (b) 400 (c) 800
  2. 2.Best estimate of 98 × 52? (a) 5000 (b) 500 (c) 50000
  3. 3.Best estimate of 159 + 651? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 339 + 578? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 667 + 331? (a) 1000 (b) 800 (c) 1200
  6. 6.Best estimate of 88 × 34? (a) 270 (b) 27000 (c) 2700
  7. 7.Best estimate of 378 + 483? (a) 900 (b) 1100 (c) 700
  8. 8.Best estimate of 51 × 46? (a) 25000 (b) 250 (c) 2500
  9. 9.Best estimate of 384 + 267? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 790 + 416? (a) 1400 (b) 1200 (c) 1000
  11. 11.Best estimate of 323 + 822? (a) 1100 (b) 1300 (c) 900
  12. 12.Best estimate of 388 + 336? (a) 900 (b) 500 (c) 700
  13. 13.Best estimate of 32 × 48? (a) 1500 (b) 15000 (c) 150
  14. 14.Best estimate of 40 × 76? (a) 32000 (b) 320 (c) 3200
  15. 15.Best estimate of 66 × 36? (a) 28000 (b) 280 (c) 2800
  16. 16.Best estimate of 69 × 53? (a) 350 (b) 35000 (c) 3500
  17. 17.Best estimate of 603 + 766? (a) 1400 (b) 1600 (c) 1200
  18. 18.Best estimate of 446 + 800? (a) 1000 (b) 1200 (c) 1400
  19. 19.Best estimate of 41 × 29? (a) 120 (b) 12000 (c) 1200
  20. 20.Best estimate of 701 + 698? (a) 1400 (b) 1200 (c) 1600
  21. 21.Best estimate of 71 × 34? (a) 210 (b) 21000 (c) 2100
  22. 22.Best estimate of 63 × 96? (a) 6000 (b) 600 (c) 60000
  23. 23.Best estimate of 443 + 323? (a) 700 (b) 500 (c) 900
  24. 24.Best estimate of 43 × 29? (a) 1200 (b) 12000 (c) 120
  25. 25.Best estimate of 385 + 823? (a) 1000 (b) 1400 (c) 1200
  26. 26.Best estimate of 36 × 37? (a) 16000 (b) 160 (c) 1600
  27. 27.Best estimate of 24 × 16? (a) 400 (b) 4000 (c) 40
  28. 28.Best estimate of 51 × 79? (a) 40000 (b) 4000 (c) 400
  29. 29.Best estimate of 12 × 80? (a) 8000 (b) 80 (c) 800
  30. 30.Best estimate of 379 + 344? (a) 500 (b) 700 (c) 900
  31. 31.Best estimate of 50 × 84? (a) 400 (b) 40000 (c) 4000
  32. 32.Best estimate of 80 × 40? (a) 3200 (b) 32000 (c) 320
  33. 33.Best estimate of 415 + 279? (a) 700 (b) 500 (c) 900
  34. 34.Best estimate of 73 × 60? (a) 4200 (b) 420 (c) 42000
  35. 35.Best estimate of 14 × 44? (a) 4000 (b) 400 (c) 40
  36. 36.Best estimate of 91 × 76? (a) 720 (b) 72000 (c) 7200
  37. 37.Best estimate of 93 × 66? (a) 6300 (b) 63000 (c) 630
  38. 38.Best estimate of 53 × 38? (a) 2000 (b) 20000 (c) 200
  39. 39.Best estimate of 64 × 96? (a) 6000 (b) 600 (c) 60000
  40. 40.Best estimate of 802 + 795? (a) 1600 (b) 1800 (c) 1400

Answer key

  1. 600
  2. 5000
  3. 900
  4. 900
  5. 1000
  6. 2700
  7. 900
  8. 2500
  9. 700
  10. 1200
  11. 1100
  12. 700
  13. 1500
  14. 3200
  15. 2800
  16. 3500
  17. 1400
  18. 1200
  19. 1200
  20. 1400
  21. 2100
  22. 6000
  23. 700
  24. 1200
  25. 1200
  26. 1600
  27. 400
  28. 4000
  29. 800
  30. 700
  31. 4000
  32. 3200
  33. 700
  34. 4200
  35. 400
  36. 7200
  37. 6300
  38. 2000
  39. 6000
  40. 1600

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