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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 423 · 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 349 + 579? (a) 1100 (b) 700 (c) 900
  2. 2.Best estimate of 94 × 94? (a) 81000 (b) 8100 (c) 810
  3. 3.Best estimate of 59 × 16? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 83 × 34? (a) 2400 (b) 240 (c) 24000
  5. 5.Best estimate of 72 × 44? (a) 2800 (b) 280 (c) 28000
  6. 6.Best estimate of 647 + 311? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 51 × 82? (a) 400 (b) 40000 (c) 4000
  8. 8.Best estimate of 30 × 59? (a) 1800 (b) 18000 (c) 180
  9. 9.Best estimate of 752 + 633? (a) 1600 (b) 1200 (c) 1400
  10. 10.Best estimate of 121 + 271? (a) 200 (b) 400 (c) 600
  11. 11.Best estimate of 43 × 86? (a) 36000 (b) 3600 (c) 360
  12. 12.Best estimate of 190 + 616? (a) 1000 (b) 600 (c) 800
  13. 13.Best estimate of 36 × 50? (a) 200 (b) 2000 (c) 20000
  14. 14.Best estimate of 19 × 63? (a) 12000 (b) 1200 (c) 120
  15. 15.Best estimate of 144 + 515? (a) 600 (b) 800 (c) 400
  16. 16.Best estimate of 432 + 639? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 473 + 765? (a) 1500 (b) 1100 (c) 1300
  18. 18.Best estimate of 701 + 263? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 46 × 32? (a) 1500 (b) 150 (c) 15000
  20. 20.Best estimate of 36 × 26? (a) 120 (b) 12000 (c) 1200
  21. 21.Best estimate of 219 + 262? (a) 300 (b) 500 (c) 700
  22. 22.Best estimate of 72 × 60? (a) 4200 (b) 420 (c) 42000
  23. 23.Best estimate of 23 × 20? (a) 400 (b) 4000 (c) 40
  24. 24.Best estimate of 16 × 72? (a) 1400 (b) 14000 (c) 140
  25. 25.Best estimate of 87 × 62? (a) 540 (b) 5400 (c) 54000
  26. 26.Best estimate of 743 + 563? (a) 1300 (b) 1500 (c) 1100
  27. 27.Best estimate of 386 + 787? (a) 1400 (b) 1200 (c) 1000
  28. 28.Best estimate of 80 × 86? (a) 72000 (b) 720 (c) 7200
  29. 29.Best estimate of 34 × 31? (a) 9000 (b) 90 (c) 900
  30. 30.Best estimate of 59 × 37? (a) 24000 (b) 2400 (c) 240
  31. 31.Best estimate of 509 + 419? (a) 700 (b) 900 (c) 1100
  32. 32.Best estimate of 76 × 38? (a) 320 (b) 32000 (c) 3200
  33. 33.Best estimate of 31 × 91? (a) 2700 (b) 27000 (c) 270
  34. 34.Best estimate of 56 × 26? (a) 180 (b) 1800 (c) 18000
  35. 35.Best estimate of 236 + 863? (a) 900 (b) 1100 (c) 1300
  36. 36.Best estimate of 824 + 218? (a) 1000 (b) 1200 (c) 800
  37. 37.Best estimate of 386 + 469? (a) 900 (b) 700 (c) 1100
  38. 38.Best estimate of 524 + 242? (a) 900 (b) 500 (c) 700
  39. 39.Best estimate of 40 × 60? (a) 24000 (b) 240 (c) 2400
  40. 40.Best estimate of 76 × 51? (a) 4000 (b) 400 (c) 40000

Answer key

  1. 900
  2. 8100
  3. 1200
  4. 2400
  5. 2800
  6. 900
  7. 4000
  8. 1800
  9. 1400
  10. 400
  11. 3600
  12. 800
  13. 2000
  14. 1200
  15. 600
  16. 1000
  17. 1300
  18. 1000
  19. 1500
  20. 1200
  21. 500
  22. 4200
  23. 400
  24. 1400
  25. 5400
  26. 1300
  27. 1200
  28. 7200
  29. 900
  30. 2400
  31. 900
  32. 3200
  33. 2700
  34. 1800
  35. 1100
  36. 1000
  37. 900
  38. 700
  39. 2400
  40. 4000

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