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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 684 · 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 184 + 630? (a) 600 (b) 1000 (c) 800
  2. 2.Best estimate of 90 × 66? (a) 63000 (b) 6300 (c) 630
  3. 3.Best estimate of 202 + 280? (a) 300 (b) 500 (c) 700
  4. 4.Best estimate of 772 + 160? (a) 1000 (b) 1200 (c) 800
  5. 5.Best estimate of 22 × 97? (a) 200 (b) 2000 (c) 20000
  6. 6.Best estimate of 139 + 711? (a) 800 (b) 600 (c) 1000
  7. 7.Best estimate of 44 × 17? (a) 80 (b) 800 (c) 8000
  8. 8.Best estimate of 333 + 546? (a) 1000 (b) 600 (c) 800
  9. 9.Best estimate of 39 × 16? (a) 80 (b) 8000 (c) 800
  10. 10.Best estimate of 23 × 76? (a) 16000 (b) 160 (c) 1600
  11. 11.Best estimate of 356 + 632? (a) 800 (b) 1200 (c) 1000
  12. 12.Best estimate of 21 × 66? (a) 1400 (b) 140 (c) 14000
  13. 13.Best estimate of 33 × 59? (a) 180 (b) 1800 (c) 18000
  14. 14.Best estimate of 60 × 81? (a) 4800 (b) 48000 (c) 480
  15. 15.Best estimate of 63 × 64? (a) 36000 (b) 3600 (c) 360
  16. 16.Best estimate of 369 + 710? (a) 900 (b) 1300 (c) 1100
  17. 17.Best estimate of 79 × 26? (a) 24000 (b) 240 (c) 2400
  18. 18.Best estimate of 314 + 851? (a) 1200 (b) 1400 (c) 1000
  19. 19.Best estimate of 485 + 633? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 570 + 421? (a) 800 (b) 1000 (c) 1200
  21. 21.Best estimate of 96 × 91? (a) 90000 (b) 900 (c) 9000
  22. 22.Best estimate of 74 × 47? (a) 3500 (b) 35000 (c) 350
  23. 23.Best estimate of 16 × 16? (a) 400 (b) 4000 (c) 40
  24. 24.Best estimate of 155 + 395? (a) 400 (b) 800 (c) 600
  25. 25.Best estimate of 46 × 17? (a) 1000 (b) 10000 (c) 100
  26. 26.Best estimate of 670 + 218? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 31 × 46? (a) 150 (b) 1500 (c) 15000
  28. 28.Best estimate of 189 + 479? (a) 500 (b) 900 (c) 700
  29. 29.Best estimate of 96 × 16? (a) 200 (b) 2000 (c) 20000
  30. 30.Best estimate of 98 × 23? (a) 2000 (b) 200 (c) 20000
  31. 31.Best estimate of 698 + 345? (a) 1000 (b) 1200 (c) 800
  32. 32.Best estimate of 258 + 297? (a) 400 (b) 800 (c) 600
  33. 33.Best estimate of 26 × 14? (a) 3000 (b) 30 (c) 300
  34. 34.Best estimate of 46 × 70? (a) 350 (b) 35000 (c) 3500
  35. 35.Best estimate of 496 + 804? (a) 1100 (b) 1500 (c) 1300
  36. 36.Best estimate of 242 + 316? (a) 700 (b) 500 (c) 300
  37. 37.Best estimate of 60 × 26? (a) 18000 (b) 1800 (c) 180
  38. 38.Best estimate of 691 + 411? (a) 1100 (b) 900 (c) 1300
  39. 39.Best estimate of 22 × 22? (a) 4000 (b) 40 (c) 400
  40. 40.Best estimate of 638 + 472? (a) 1100 (b) 1300 (c) 900

Answer key

  1. 800
  2. 6300
  3. 500
  4. 1000
  5. 2000
  6. 800
  7. 800
  8. 800
  9. 800
  10. 1600
  11. 1000
  12. 1400
  13. 1800
  14. 4800
  15. 3600
  16. 1100
  17. 2400
  18. 1200
  19. 1100
  20. 1000
  21. 9000
  22. 3500
  23. 400
  24. 600
  25. 1000
  26. 900
  27. 1500
  28. 700
  29. 2000
  30. 2000
  31. 1000
  32. 600
  33. 300
  34. 3500
  35. 1300
  36. 500
  37. 1800
  38. 1100
  39. 400
  40. 1100

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