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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 779 · 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 287 + 644? (a) 900 (b) 700 (c) 1100
  2. 2.Best estimate of 281 + 847? (a) 900 (b) 1100 (c) 1300
  3. 3.Best estimate of 517 + 514? (a) 1200 (b) 800 (c) 1000
  4. 4.Best estimate of 788 + 414? (a) 1000 (b) 1200 (c) 1400
  5. 5.Best estimate of 31 × 53? (a) 15000 (b) 1500 (c) 150
  6. 6.Best estimate of 38 × 53? (a) 2000 (b) 200 (c) 20000
  7. 7.Best estimate of 22 × 76? (a) 160 (b) 16000 (c) 1600
  8. 8.Best estimate of 359 + 477? (a) 900 (b) 700 (c) 1100
  9. 9.Best estimate of 36 × 41? (a) 1600 (b) 16000 (c) 160
  10. 10.Best estimate of 42 × 68? (a) 28000 (b) 2800 (c) 280
  11. 11.Best estimate of 63 × 77? (a) 480 (b) 4800 (c) 48000
  12. 12.Best estimate of 88 × 97? (a) 900 (b) 90000 (c) 9000
  13. 13.Best estimate of 54 × 81? (a) 4000 (b) 40000 (c) 400
  14. 14.Best estimate of 370 + 429? (a) 1000 (b) 600 (c) 800
  15. 15.Best estimate of 18 × 62? (a) 120 (b) 1200 (c) 12000
  16. 16.Best estimate of 12 × 28? (a) 30 (b) 3000 (c) 300
  17. 17.Best estimate of 728 + 191? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 26 × 72? (a) 210 (b) 21000 (c) 2100
  19. 19.Best estimate of 48 × 32? (a) 1500 (b) 150 (c) 15000
  20. 20.Best estimate of 41 × 82? (a) 32000 (b) 320 (c) 3200
  21. 21.Best estimate of 16 × 96? (a) 200 (b) 2000 (c) 20000
  22. 22.Best estimate of 284 + 273? (a) 800 (b) 400 (c) 600
  23. 23.Best estimate of 20 × 38? (a) 80 (b) 8000 (c) 800
  24. 24.Best estimate of 193 + 272? (a) 700 (b) 300 (c) 500
  25. 25.Best estimate of 96 × 26? (a) 30000 (b) 3000 (c) 300
  26. 26.Best estimate of 56 × 13? (a) 6000 (b) 60 (c) 600
  27. 27.Best estimate of 96 × 16? (a) 2000 (b) 200 (c) 20000
  28. 28.Best estimate of 583 + 722? (a) 1500 (b) 1100 (c) 1300
  29. 29.Best estimate of 37 × 42? (a) 16000 (b) 160 (c) 1600
  30. 30.Best estimate of 32 × 86? (a) 2700 (b) 27000 (c) 270
  31. 31.Best estimate of 21 × 84? (a) 1600 (b) 16000 (c) 160
  32. 32.Best estimate of 66 × 20? (a) 1400 (b) 140 (c) 14000
  33. 33.Best estimate of 31 × 61? (a) 180 (b) 18000 (c) 1800
  34. 34.Best estimate of 552 + 547? (a) 1300 (b) 1100 (c) 900
  35. 35.Best estimate of 588 + 679? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 40 × 30? (a) 120 (b) 12000 (c) 1200
  37. 37.Best estimate of 702 + 566? (a) 1300 (b) 1500 (c) 1100
  38. 38.Best estimate of 162 + 536? (a) 500 (b) 700 (c) 900
  39. 39.Best estimate of 76 × 27? (a) 24000 (b) 2400 (c) 240
  40. 40.Best estimate of 152 + 599? (a) 1000 (b) 600 (c) 800

Answer key

  1. 900
  2. 1100
  3. 1000
  4. 1200
  5. 1500
  6. 2000
  7. 1600
  8. 900
  9. 1600
  10. 2800
  11. 4800
  12. 9000
  13. 4000
  14. 800
  15. 1200
  16. 300
  17. 900
  18. 2100
  19. 1500
  20. 3200
  21. 2000
  22. 600
  23. 800
  24. 500
  25. 3000
  26. 600
  27. 2000
  28. 1300
  29. 1600
  30. 2700
  31. 1600
  32. 1400
  33. 1800
  34. 1100
  35. 1300
  36. 1200
  37. 1300
  38. 700
  39. 2400
  40. 800

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