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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 158 · 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 97 × 16? (a) 2000 (b) 200 (c) 20000
  2. 2.Best estimate of 760 + 320? (a) 1300 (b) 1100 (c) 900
  3. 3.Best estimate of 399 + 563? (a) 1200 (b) 1000 (c) 800
  4. 4.Best estimate of 93 × 66? (a) 6300 (b) 630 (c) 63000
  5. 5.Best estimate of 92 × 48? (a) 4500 (b) 45000 (c) 450
  6. 6.Best estimate of 412 + 777? (a) 1200 (b) 1000 (c) 1400
  7. 7.Best estimate of 97 × 27? (a) 3000 (b) 300 (c) 30000
  8. 8.Best estimate of 57 × 70? (a) 4200 (b) 420 (c) 42000
  9. 9.Best estimate of 23 × 64? (a) 120 (b) 1200 (c) 12000
  10. 10.Best estimate of 215 + 735? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 231 + 506? (a) 900 (b) 500 (c) 700
  12. 12.Best estimate of 27 × 46? (a) 15000 (b) 150 (c) 1500
  13. 13.Best estimate of 58 × 26? (a) 1800 (b) 180 (c) 18000
  14. 14.Best estimate of 28 × 23? (a) 6000 (b) 600 (c) 60
  15. 15.Best estimate of 422 + 779? (a) 1400 (b) 1200 (c) 1000
  16. 16.Best estimate of 466 + 285? (a) 600 (b) 800 (c) 1000
  17. 17.Best estimate of 98 × 51? (a) 5000 (b) 50000 (c) 500
  18. 18.Best estimate of 56 × 80? (a) 480 (b) 4800 (c) 48000
  19. 19.Best estimate of 166 + 731? (a) 900 (b) 1100 (c) 700
  20. 20.Best estimate of 305 + 298? (a) 400 (b) 600 (c) 800
  21. 21.Best estimate of 86 × 37? (a) 36000 (b) 360 (c) 3600
  22. 22.Best estimate of 54 × 27? (a) 1500 (b) 15000 (c) 150
  23. 23.Best estimate of 836 + 275? (a) 1100 (b) 900 (c) 1300
  24. 24.Best estimate of 375 + 431? (a) 800 (b) 1000 (c) 600
  25. 25.Best estimate of 74 × 71? (a) 490 (b) 4900 (c) 49000
  26. 26.Best estimate of 24 × 91? (a) 180 (b) 1800 (c) 18000
  27. 27.Best estimate of 26 × 40? (a) 1200 (b) 120 (c) 12000
  28. 28.Best estimate of 46 × 28? (a) 150 (b) 1500 (c) 15000
  29. 29.Best estimate of 540 + 549? (a) 1200 (b) 1000 (c) 800
  30. 30.Best estimate of 758 + 819? (a) 1400 (b) 1800 (c) 1600
  31. 31.Best estimate of 18 × 36? (a) 80 (b) 8000 (c) 800
  32. 32.Best estimate of 339 + 300? (a) 800 (b) 400 (c) 600
  33. 33.Best estimate of 238 + 129? (a) 500 (b) 100 (c) 300
  34. 34.Best estimate of 91 × 27? (a) 270 (b) 27000 (c) 2700
  35. 35.Best estimate of 83 × 30? (a) 240 (b) 24000 (c) 2400
  36. 36.Best estimate of 856 + 287? (a) 1000 (b) 1400 (c) 1200
  37. 37.Best estimate of 58 × 12? (a) 6000 (b) 60 (c) 600
  38. 38.Best estimate of 287 + 423? (a) 500 (b) 900 (c) 700
  39. 39.Best estimate of 24 × 41? (a) 800 (b) 8000 (c) 80
  40. 40.Best estimate of 61 × 74? (a) 42000 (b) 4200 (c) 420

Answer key

  1. 2000
  2. 1100
  3. 1000
  4. 6300
  5. 4500
  6. 1200
  7. 3000
  8. 4200
  9. 1200
  10. 900
  11. 700
  12. 1500
  13. 1800
  14. 600
  15. 1200
  16. 800
  17. 5000
  18. 4800
  19. 900
  20. 600
  21. 3600
  22. 1500
  23. 1100
  24. 800
  25. 4900
  26. 1800
  27. 1200
  28. 1500
  29. 1000
  30. 1600
  31. 800
  32. 600
  33. 300
  34. 2700
  35. 2400
  36. 1200
  37. 600
  38. 700
  39. 800
  40. 4200

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