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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 863 · 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 530 + 134? (a) 400 (b) 600 (c) 800
  2. 2.Best estimate of 63 × 36? (a) 24000 (b) 240 (c) 2400
  3. 3.Best estimate of 20 × 86? (a) 1800 (b) 18000 (c) 180
  4. 4.Best estimate of 20 × 66? (a) 14000 (b) 1400 (c) 140
  5. 5.Best estimate of 820 + 711? (a) 1500 (b) 1300 (c) 1700
  6. 6.Best estimate of 17 × 66? (a) 14000 (b) 140 (c) 1400
  7. 7.Best estimate of 502 + 874? (a) 1200 (b) 1600 (c) 1400
  8. 8.Best estimate of 54 × 31? (a) 15000 (b) 150 (c) 1500
  9. 9.Best estimate of 76 × 94? (a) 7200 (b) 72000 (c) 720
  10. 10.Best estimate of 178 + 794? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 510 + 197? (a) 900 (b) 700 (c) 500
  12. 12.Best estimate of 19 × 12? (a) 200 (b) 2000 (c) 20
  13. 13.Best estimate of 98 × 70? (a) 7000 (b) 70000 (c) 700
  14. 14.Best estimate of 62 × 59? (a) 3600 (b) 36000 (c) 360
  15. 15.Best estimate of 94 × 38? (a) 3600 (b) 36000 (c) 360
  16. 16.Best estimate of 233 + 703? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 773 + 647? (a) 1600 (b) 1400 (c) 1200
  18. 18.Best estimate of 59 × 26? (a) 1800 (b) 18000 (c) 180
  19. 19.Best estimate of 579 + 448? (a) 1000 (b) 800 (c) 1200
  20. 20.Best estimate of 17 × 64? (a) 12000 (b) 1200 (c) 120
  21. 21.Best estimate of 477 + 460? (a) 1200 (b) 800 (c) 1000
  22. 22.Best estimate of 625 + 274? (a) 1100 (b) 900 (c) 700
  23. 23.Best estimate of 23 × 50? (a) 1000 (b) 10000 (c) 100
  24. 24.Best estimate of 796 + 355? (a) 1200 (b) 1400 (c) 1000
  25. 25.Best estimate of 60 × 86? (a) 5400 (b) 54000 (c) 540
  26. 26.Best estimate of 81 × 27? (a) 240 (b) 24000 (c) 2400
  27. 27.Best estimate of 338 + 201? (a) 500 (b) 300 (c) 700
  28. 28.Best estimate of 282 + 378? (a) 900 (b) 700 (c) 500
  29. 29.Best estimate of 751 + 411? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 18 × 43? (a) 8000 (b) 80 (c) 800
  31. 31.Best estimate of 86 × 47? (a) 4500 (b) 45000 (c) 450
  32. 32.Best estimate of 754 + 473? (a) 1100 (b) 1500 (c) 1300
  33. 33.Best estimate of 49 × 16? (a) 10000 (b) 100 (c) 1000
  34. 34.Best estimate of 48 × 52? (a) 25000 (b) 250 (c) 2500
  35. 35.Best estimate of 26 × 23? (a) 600 (b) 6000 (c) 60
  36. 36.Best estimate of 53 × 91? (a) 45000 (b) 4500 (c) 450
  37. 37.Best estimate of 379 + 261? (a) 900 (b) 700 (c) 500
  38. 38.Best estimate of 592 + 176? (a) 1000 (b) 600 (c) 800
  39. 39.Best estimate of 248 + 179? (a) 600 (b) 400 (c) 200
  40. 40.Best estimate of 16 × 17? (a) 40 (b) 400 (c) 4000

Answer key

  1. 600
  2. 2400
  3. 1800
  4. 1400
  5. 1500
  6. 1400
  7. 1400
  8. 1500
  9. 7200
  10. 1000
  11. 700
  12. 200
  13. 7000
  14. 3600
  15. 3600
  16. 900
  17. 1400
  18. 1800
  19. 1000
  20. 1200
  21. 1000
  22. 900
  23. 1000
  24. 1200
  25. 5400
  26. 2400
  27. 500
  28. 700
  29. 1200
  30. 800
  31. 4500
  32. 1300
  33. 1000
  34. 2500
  35. 600
  36. 4500
  37. 700
  38. 800
  39. 400
  40. 400

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