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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 422 · 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 260 + 200? (a) 500 (b) 300 (c) 700
  2. 2.Best estimate of 36 × 67? (a) 28000 (b) 2800 (c) 280
  3. 3.Best estimate of 97 × 86? (a) 9000 (b) 900 (c) 90000
  4. 4.Best estimate of 13 × 79? (a) 80 (b) 8000 (c) 800
  5. 5.Best estimate of 41 × 30? (a) 120 (b) 1200 (c) 12000
  6. 6.Best estimate of 90 × 73? (a) 63000 (b) 6300 (c) 630
  7. 7.Best estimate of 37 × 38? (a) 160 (b) 16000 (c) 1600
  8. 8.Best estimate of 73 × 26? (a) 210 (b) 21000 (c) 2100
  9. 9.Best estimate of 46 × 79? (a) 400 (b) 40000 (c) 4000
  10. 10.Best estimate of 13 × 33? (a) 30 (b) 3000 (c) 300
  11. 11.Best estimate of 545 + 395? (a) 1100 (b) 700 (c) 900
  12. 12.Best estimate of 436 + 679? (a) 1300 (b) 1100 (c) 900
  13. 13.Best estimate of 728 + 623? (a) 1100 (b) 1300 (c) 1500
  14. 14.Best estimate of 36 × 63? (a) 24000 (b) 240 (c) 2400
  15. 15.Best estimate of 67 × 49? (a) 3500 (b) 350 (c) 35000
  16. 16.Best estimate of 348 + 603? (a) 700 (b) 1100 (c) 900
  17. 17.Best estimate of 33 × 32? (a) 900 (b) 9000 (c) 90
  18. 18.Best estimate of 612 + 733? (a) 1300 (b) 1500 (c) 1100
  19. 19.Best estimate of 82 × 48? (a) 4000 (b) 40000 (c) 400
  20. 20.Best estimate of 763 + 512? (a) 1500 (b) 1100 (c) 1300
  21. 21.Best estimate of 658 + 497? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 380 + 467? (a) 1100 (b) 900 (c) 700
  23. 23.Best estimate of 36 × 37? (a) 160 (b) 1600 (c) 16000
  24. 24.Best estimate of 723 + 203? (a) 1100 (b) 900 (c) 700
  25. 25.Best estimate of 618 + 121? (a) 900 (b) 500 (c) 700
  26. 26.Best estimate of 77 × 31? (a) 2400 (b) 24000 (c) 240
  27. 27.Best estimate of 369 + 708? (a) 1100 (b) 900 (c) 1300
  28. 28.Best estimate of 84 × 38? (a) 320 (b) 32000 (c) 3200
  29. 29.Best estimate of 500 + 503? (a) 1200 (b) 1000 (c) 800
  30. 30.Best estimate of 658 + 159? (a) 700 (b) 900 (c) 1100
  31. 31.Best estimate of 308 + 264? (a) 800 (b) 600 (c) 400
  32. 32.Best estimate of 763 + 380? (a) 1200 (b) 1000 (c) 1400
  33. 33.Best estimate of 62 × 71? (a) 4200 (b) 42000 (c) 420
  34. 34.Best estimate of 251 + 200? (a) 500 (b) 700 (c) 300
  35. 35.Best estimate of 123 + 288? (a) 400 (b) 200 (c) 600
  36. 36.Best estimate of 229 + 211? (a) 200 (b) 400 (c) 600
  37. 37.Best estimate of 78 × 58? (a) 48000 (b) 4800 (c) 480
  38. 38.Best estimate of 403 + 133? (a) 300 (b) 700 (c) 500
  39. 39.Best estimate of 214 + 656? (a) 1100 (b) 700 (c) 900
  40. 40.Best estimate of 240 + 771? (a) 1200 (b) 1000 (c) 800

Answer key

  1. 500
  2. 2800
  3. 9000
  4. 800
  5. 1200
  6. 6300
  7. 1600
  8. 2100
  9. 4000
  10. 300
  11. 900
  12. 1100
  13. 1300
  14. 2400
  15. 3500
  16. 900
  17. 900
  18. 1300
  19. 4000
  20. 1300
  21. 1200
  22. 900
  23. 1600
  24. 900
  25. 700
  26. 2400
  27. 1100
  28. 3200
  29. 1000
  30. 900
  31. 600
  32. 1200
  33. 4200
  34. 500
  35. 400
  36. 400
  37. 4800
  38. 500
  39. 900
  40. 1000

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