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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 628 · 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 124 + 429? (a) 300 (b) 700 (c) 500
  2. 2.Best estimate of 610 + 864? (a) 1500 (b) 1700 (c) 1300
  3. 3.Best estimate of 41 × 59? (a) 24000 (b) 2400 (c) 240
  4. 4.Best estimate of 534 + 729? (a) 1000 (b) 1200 (c) 1400
  5. 5.Best estimate of 593 + 153? (a) 800 (b) 600 (c) 1000
  6. 6.Best estimate of 244 + 348? (a) 300 (b) 500 (c) 700
  7. 7.Best estimate of 267 + 790? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 592 + 458? (a) 1100 (b) 1300 (c) 900
  9. 9.Best estimate of 504 + 210? (a) 900 (b) 500 (c) 700
  10. 10.Best estimate of 603 + 402? (a) 1200 (b) 1000 (c) 800
  11. 11.Best estimate of 579 + 771? (a) 1600 (b) 1200 (c) 1400
  12. 12.Best estimate of 754 + 246? (a) 1000 (b) 800 (c) 1200
  13. 13.Best estimate of 520 + 126? (a) 400 (b) 600 (c) 800
  14. 14.Best estimate of 240 + 687? (a) 1100 (b) 900 (c) 700
  15. 15.Best estimate of 76 × 16? (a) 16000 (b) 160 (c) 1600
  16. 16.Best estimate of 668 + 439? (a) 900 (b) 1300 (c) 1100
  17. 17.Best estimate of 846 + 504? (a) 1500 (b) 1300 (c) 1100
  18. 18.Best estimate of 123 + 835? (a) 1100 (b) 700 (c) 900
  19. 19.Best estimate of 18 × 44? (a) 800 (b) 8000 (c) 80
  20. 20.Best estimate of 17 × 31? (a) 600 (b) 6000 (c) 60
  21. 21.Best estimate of 879 + 518? (a) 1200 (b) 1400 (c) 1600
  22. 22.Best estimate of 27 × 14? (a) 30 (b) 3000 (c) 300
  23. 23.Best estimate of 642 + 223? (a) 1000 (b) 600 (c) 800
  24. 24.Best estimate of 46 × 36? (a) 2000 (b) 200 (c) 20000
  25. 25.Best estimate of 633 + 256? (a) 1100 (b) 900 (c) 700
  26. 26.Best estimate of 432 + 333? (a) 900 (b) 500 (c) 700
  27. 27.Best estimate of 17 × 78? (a) 16000 (b) 1600 (c) 160
  28. 28.Best estimate of 254 + 627? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 145 + 189? (a) 500 (b) 300 (c) 100
  30. 30.Best estimate of 36 × 28? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 143 + 421? (a) 700 (b) 300 (c) 500
  32. 32.Best estimate of 448 + 156? (a) 800 (b) 400 (c) 600
  33. 33.Best estimate of 402 + 760? (a) 1200 (b) 1000 (c) 1400
  34. 34.Best estimate of 36 × 31? (a) 120 (b) 12000 (c) 1200
  35. 35.Best estimate of 83 × 28? (a) 2400 (b) 24000 (c) 240
  36. 36.Best estimate of 80 × 22? (a) 160 (b) 1600 (c) 16000
  37. 37.Best estimate of 777 + 377? (a) 1400 (b) 1000 (c) 1200
  38. 38.Best estimate of 247 + 783? (a) 1200 (b) 800 (c) 1000
  39. 39.Best estimate of 60 × 73? (a) 420 (b) 4200 (c) 42000
  40. 40.Best estimate of 328 + 321? (a) 800 (b) 600 (c) 400

Answer key

  1. 500
  2. 1500
  3. 2400
  4. 1200
  5. 800
  6. 500
  7. 1100
  8. 1100
  9. 700
  10. 1000
  11. 1400
  12. 1000
  13. 600
  14. 900
  15. 1600
  16. 1100
  17. 1300
  18. 900
  19. 800
  20. 600
  21. 1400
  22. 300
  23. 800
  24. 2000
  25. 900
  26. 700
  27. 1600
  28. 900
  29. 300
  30. 1200
  31. 500
  32. 600
  33. 1200
  34. 1200
  35. 2400
  36. 1600
  37. 1200
  38. 1000
  39. 4200
  40. 600

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