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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 280 · 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 266 + 403? (a) 700 (b) 500 (c) 900
  2. 2.Best estimate of 173 + 464? (a) 700 (b) 900 (c) 500
  3. 3.Best estimate of 693 + 282? (a) 800 (b) 1000 (c) 1200
  4. 4.Best estimate of 14 × 86? (a) 90 (b) 900 (c) 9000
  5. 5.Best estimate of 77 × 84? (a) 64000 (b) 640 (c) 6400
  6. 6.Best estimate of 41 × 46? (a) 2000 (b) 20000 (c) 200
  7. 7.Best estimate of 51 × 36? (a) 2000 (b) 200 (c) 20000
  8. 8.Best estimate of 208 + 692? (a) 700 (b) 900 (c) 1100
  9. 9.Best estimate of 351 + 185? (a) 400 (b) 600 (c) 800
  10. 10.Best estimate of 60 × 24? (a) 1200 (b) 120 (c) 12000
  11. 11.Best estimate of 639 + 196? (a) 600 (b) 1000 (c) 800
  12. 12.Best estimate of 699 + 461? (a) 1400 (b) 1000 (c) 1200
  13. 13.Best estimate of 87 × 86? (a) 81000 (b) 8100 (c) 810
  14. 14.Best estimate of 69 × 96? (a) 700 (b) 70000 (c) 7000
  15. 15.Best estimate of 12 × 70? (a) 700 (b) 70 (c) 7000
  16. 16.Best estimate of 57 × 29? (a) 18000 (b) 1800 (c) 180
  17. 17.Best estimate of 69 × 69? (a) 490 (b) 49000 (c) 4900
  18. 18.Best estimate of 412 + 622? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 230 + 658? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 76 × 94? (a) 7200 (b) 720 (c) 72000
  21. 21.Best estimate of 31 × 33? (a) 900 (b) 9000 (c) 90
  22. 22.Best estimate of 67 × 97? (a) 700 (b) 70000 (c) 7000
  23. 23.Best estimate of 72 × 28? (a) 210 (b) 2100 (c) 21000
  24. 24.Best estimate of 414 + 173? (a) 800 (b) 600 (c) 400
  25. 25.Best estimate of 72 × 26? (a) 2100 (b) 21000 (c) 210
  26. 26.Best estimate of 791 + 527? (a) 1100 (b) 1300 (c) 1500
  27. 27.Best estimate of 50 × 78? (a) 400 (b) 4000 (c) 40000
  28. 28.Best estimate of 27 × 24? (a) 6000 (b) 600 (c) 60
  29. 29.Best estimate of 76 × 14? (a) 80 (b) 8000 (c) 800
  30. 30.Best estimate of 380 + 691? (a) 900 (b) 1100 (c) 1300
  31. 31.Best estimate of 152 + 565? (a) 600 (b) 800 (c) 1000
  32. 32.Best estimate of 548 + 140? (a) 400 (b) 600 (c) 800
  33. 33.Best estimate of 267 + 605? (a) 700 (b) 900 (c) 1100
  34. 34.Best estimate of 384 + 169? (a) 400 (b) 800 (c) 600
  35. 35.Best estimate of 80 × 82? (a) 640 (b) 64000 (c) 6400
  36. 36.Best estimate of 393 + 334? (a) 500 (b) 700 (c) 900
  37. 37.Best estimate of 229 + 263? (a) 300 (b) 700 (c) 500
  38. 38.Best estimate of 694 + 281? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 78 × 46? (a) 4000 (b) 40000 (c) 400
  40. 40.Best estimate of 37 × 77? (a) 3200 (b) 32000 (c) 320

Answer key

  1. 700
  2. 700
  3. 1000
  4. 900
  5. 6400
  6. 2000
  7. 2000
  8. 900
  9. 600
  10. 1200
  11. 800
  12. 1200
  13. 8100
  14. 7000
  15. 700
  16. 1800
  17. 4900
  18. 1000
  19. 900
  20. 7200
  21. 900
  22. 7000
  23. 2100
  24. 600
  25. 2100
  26. 1300
  27. 4000
  28. 600
  29. 800
  30. 1100
  31. 800
  32. 600
  33. 900
  34. 600
  35. 6400
  36. 700
  37. 500
  38. 1000
  39. 4000
  40. 3200

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