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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 819 · 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 69 × 76? (a) 560 (b) 5600 (c) 56000
  2. 2.Best estimate of 63 × 47? (a) 30000 (b) 300 (c) 3000
  3. 3.Best estimate of 66 × 70? (a) 4900 (b) 490 (c) 49000
  4. 4.Best estimate of 436 + 169? (a) 400 (b) 600 (c) 800
  5. 5.Best estimate of 31 × 57? (a) 18000 (b) 180 (c) 1800
  6. 6.Best estimate of 36 × 79? (a) 320 (b) 3200 (c) 32000
  7. 7.Best estimate of 72 × 73? (a) 490 (b) 4900 (c) 49000
  8. 8.Best estimate of 473 + 281? (a) 1000 (b) 800 (c) 600
  9. 9.Best estimate of 37 × 12? (a) 400 (b) 4000 (c) 40
  10. 10.Best estimate of 622 + 294? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 38 × 22? (a) 800 (b) 8000 (c) 80
  12. 12.Best estimate of 84 × 38? (a) 32000 (b) 3200 (c) 320
  13. 13.Best estimate of 48 × 17? (a) 100 (b) 10000 (c) 1000
  14. 14.Best estimate of 202 + 588? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 677 + 227? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 643 + 709? (a) 1500 (b) 1300 (c) 1100
  17. 17.Best estimate of 855 + 785? (a) 1700 (b) 1900 (c) 1500
  18. 18.Best estimate of 13 × 16? (a) 2000 (b) 200 (c) 20
  19. 19.Best estimate of 20 × 27? (a) 60 (b) 600 (c) 6000
  20. 20.Best estimate of 643 + 807? (a) 1400 (b) 1600 (c) 1200
  21. 21.Best estimate of 864 + 520? (a) 1400 (b) 1600 (c) 1200
  22. 22.Best estimate of 56 × 31? (a) 180 (b) 1800 (c) 18000
  23. 23.Best estimate of 809 + 277? (a) 1100 (b) 1300 (c) 900
  24. 24.Best estimate of 871 + 440? (a) 1100 (b) 1300 (c) 1500
  25. 25.Best estimate of 87 × 44? (a) 3600 (b) 36000 (c) 360
  26. 26.Best estimate of 24 × 66? (a) 14000 (b) 140 (c) 1400
  27. 27.Best estimate of 184 + 727? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 78 × 16? (a) 1600 (b) 16000 (c) 160
  29. 29.Best estimate of 354 + 800? (a) 1200 (b) 1000 (c) 1400
  30. 30.Best estimate of 365 + 168? (a) 800 (b) 600 (c) 400
  31. 31.Best estimate of 22 × 42? (a) 8000 (b) 800 (c) 80
  32. 32.Best estimate of 96 × 12? (a) 10000 (b) 1000 (c) 100
  33. 33.Best estimate of 21 × 64? (a) 1200 (b) 12000 (c) 120
  34. 34.Best estimate of 90 × 17? (a) 180 (b) 18000 (c) 1800
  35. 35.Best estimate of 39 × 50? (a) 200 (b) 2000 (c) 20000
  36. 36.Best estimate of 52 × 79? (a) 400 (b) 40000 (c) 4000
  37. 37.Best estimate of 489 + 157? (a) 500 (b) 700 (c) 900
  38. 38.Best estimate of 651 + 380? (a) 900 (b) 1300 (c) 1100
  39. 39.Best estimate of 77 × 63? (a) 480 (b) 48000 (c) 4800
  40. 40.Best estimate of 44 × 74? (a) 28000 (b) 2800 (c) 280

Answer key

  1. 5600
  2. 3000
  3. 4900
  4. 600
  5. 1800
  6. 3200
  7. 4900
  8. 800
  9. 400
  10. 900
  11. 800
  12. 3200
  13. 1000
  14. 800
  15. 900
  16. 1300
  17. 1700
  18. 200
  19. 600
  20. 1400
  21. 1400
  22. 1800
  23. 1100
  24. 1300
  25. 3600
  26. 1400
  27. 900
  28. 1600
  29. 1200
  30. 600
  31. 800
  32. 1000
  33. 1200
  34. 1800
  35. 2000
  36. 4000
  37. 700
  38. 1100
  39. 4800
  40. 2800

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