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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 645 · 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 518 + 703? (a) 1200 (b) 1400 (c) 1000
  2. 2.Best estimate of 56 × 98? (a) 60000 (b) 6000 (c) 600
  3. 3.Best estimate of 97 × 21? (a) 200 (b) 2000 (c) 20000
  4. 4.Best estimate of 36 × 62? (a) 2400 (b) 240 (c) 24000
  5. 5.Best estimate of 89 × 21? (a) 1800 (b) 180 (c) 18000
  6. 6.Best estimate of 176 + 749? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 344 + 681? (a) 1200 (b) 1000 (c) 800
  8. 8.Best estimate of 615 + 863? (a) 1500 (b) 1300 (c) 1700
  9. 9.Best estimate of 500 + 308? (a) 800 (b) 600 (c) 1000
  10. 10.Best estimate of 73 × 22? (a) 140 (b) 1400 (c) 14000
  11. 11.Best estimate of 66 × 20? (a) 1400 (b) 140 (c) 14000
  12. 12.Best estimate of 583 + 880? (a) 1500 (b) 1300 (c) 1700
  13. 13.Best estimate of 19 × 49? (a) 100 (b) 1000 (c) 10000
  14. 14.Best estimate of 356 + 745? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 552 + 782? (a) 1400 (b) 1200 (c) 1600
  16. 16.Best estimate of 259 + 295? (a) 600 (b) 800 (c) 400
  17. 17.Best estimate of 44 × 29? (a) 12000 (b) 120 (c) 1200
  18. 18.Best estimate of 97 × 88? (a) 900 (b) 9000 (c) 90000
  19. 19.Best estimate of 41 × 12? (a) 4000 (b) 40 (c) 400
  20. 20.Best estimate of 341 + 465? (a) 1000 (b) 800 (c) 600
  21. 21.Best estimate of 369 + 841? (a) 1400 (b) 1200 (c) 1000
  22. 22.Best estimate of 642 + 566? (a) 1200 (b) 1000 (c) 1400
  23. 23.Best estimate of 77 × 33? (a) 2400 (b) 240 (c) 24000
  24. 24.Best estimate of 32 × 74? (a) 2100 (b) 210 (c) 21000
  25. 25.Best estimate of 84 × 28? (a) 2400 (b) 24000 (c) 240
  26. 26.Best estimate of 30 × 36? (a) 120 (b) 1200 (c) 12000
  27. 27.Best estimate of 229 + 686? (a) 900 (b) 700 (c) 1100
  28. 28.Best estimate of 36 × 81? (a) 320 (b) 32000 (c) 3200
  29. 29.Best estimate of 26 × 47? (a) 150 (b) 15000 (c) 1500
  30. 30.Best estimate of 56 × 43? (a) 24000 (b) 240 (c) 2400
  31. 31.Best estimate of 785 + 612? (a) 1600 (b) 1400 (c) 1200
  32. 32.Best estimate of 82 × 46? (a) 40000 (b) 400 (c) 4000
  33. 33.Best estimate of 60 × 58? (a) 36000 (b) 360 (c) 3600
  34. 34.Best estimate of 651 + 317? (a) 800 (b) 1000 (c) 1200
  35. 35.Best estimate of 73 × 56? (a) 42000 (b) 420 (c) 4200
  36. 36.Best estimate of 297 + 652? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 37 × 54? (a) 200 (b) 20000 (c) 2000
  38. 38.Best estimate of 80 × 96? (a) 800 (b) 80000 (c) 8000
  39. 39.Best estimate of 807 + 583? (a) 1600 (b) 1200 (c) 1400
  40. 40.Best estimate of 797 + 692? (a) 1700 (b) 1500 (c) 1300

Answer key

  1. 1200
  2. 6000
  3. 2000
  4. 2400
  5. 1800
  6. 900
  7. 1000
  8. 1500
  9. 800
  10. 1400
  11. 1400
  12. 1500
  13. 1000
  14. 1100
  15. 1400
  16. 600
  17. 1200
  18. 9000
  19. 400
  20. 800
  21. 1200
  22. 1200
  23. 2400
  24. 2100
  25. 2400
  26. 1200
  27. 900
  28. 3200
  29. 1500
  30. 2400
  31. 1400
  32. 4000
  33. 3600
  34. 1000
  35. 4200
  36. 1000
  37. 2000
  38. 8000
  39. 1400
  40. 1500

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