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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 428 · 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 16 × 56? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 382 + 618? (a) 800 (b) 1000 (c) 1200
  3. 3.Best estimate of 56 × 33? (a) 18000 (b) 1800 (c) 180
  4. 4.Best estimate of 468 + 493? (a) 1000 (b) 800 (c) 1200
  5. 5.Best estimate of 659 + 508? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 723 + 676? (a) 1600 (b) 1400 (c) 1200
  7. 7.Best estimate of 63 × 13? (a) 60 (b) 600 (c) 6000
  8. 8.Best estimate of 83 × 89? (a) 7200 (b) 72000 (c) 720
  9. 9.Best estimate of 658 + 681? (a) 1600 (b) 1400 (c) 1200
  10. 10.Best estimate of 26 × 38? (a) 1200 (b) 120 (c) 12000
  11. 11.Best estimate of 588 + 842? (a) 1600 (b) 1400 (c) 1200
  12. 12.Best estimate of 49 × 40? (a) 2000 (b) 200 (c) 20000
  13. 13.Best estimate of 48 × 60? (a) 30000 (b) 3000 (c) 300
  14. 14.Best estimate of 417 + 658? (a) 900 (b) 1100 (c) 1300
  15. 15.Best estimate of 475 + 459? (a) 1200 (b) 800 (c) 1000
  16. 16.Best estimate of 161 + 638? (a) 600 (b) 800 (c) 1000
  17. 17.Best estimate of 143 + 672? (a) 800 (b) 1000 (c) 600
  18. 18.Best estimate of 41 × 26? (a) 1200 (b) 12000 (c) 120
  19. 19.Best estimate of 36 × 61? (a) 2400 (b) 240 (c) 24000
  20. 20.Best estimate of 70 × 18? (a) 14000 (b) 140 (c) 1400
  21. 21.Best estimate of 279 + 402? (a) 700 (b) 500 (c) 900
  22. 22.Best estimate of 46 × 81? (a) 4000 (b) 40000 (c) 400
  23. 23.Best estimate of 74 × 19? (a) 1400 (b) 140 (c) 14000
  24. 24.Best estimate of 23 × 70? (a) 140 (b) 1400 (c) 14000
  25. 25.Best estimate of 16 × 31? (a) 600 (b) 6000 (c) 60
  26. 26.Best estimate of 36 × 20? (a) 8000 (b) 800 (c) 80
  27. 27.Best estimate of 39 × 70? (a) 2800 (b) 28000 (c) 280
  28. 28.Best estimate of 16 × 66? (a) 14000 (b) 1400 (c) 140
  29. 29.Best estimate of 60 × 80? (a) 4800 (b) 48000 (c) 480
  30. 30.Best estimate of 29 × 38? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 44 × 20? (a) 800 (b) 8000 (c) 80
  32. 32.Best estimate of 77 × 97? (a) 80000 (b) 8000 (c) 800
  33. 33.Best estimate of 17 × 19? (a) 400 (b) 4000 (c) 40
  34. 34.Best estimate of 26 × 41? (a) 120 (b) 12000 (c) 1200
  35. 35.Best estimate of 90 × 20? (a) 1800 (b) 180 (c) 18000
  36. 36.Best estimate of 27 × 12? (a) 30 (b) 3000 (c) 300
  37. 37.Best estimate of 242 + 588? (a) 1000 (b) 800 (c) 600
  38. 38.Best estimate of 94 × 32? (a) 2700 (b) 270 (c) 27000
  39. 39.Best estimate of 216 + 217? (a) 600 (b) 200 (c) 400
  40. 40.Best estimate of 516 + 331? (a) 800 (b) 600 (c) 1000

Answer key

  1. 1200
  2. 1000
  3. 1800
  4. 1000
  5. 1200
  6. 1400
  7. 600
  8. 7200
  9. 1400
  10. 1200
  11. 1400
  12. 2000
  13. 3000
  14. 1100
  15. 1000
  16. 800
  17. 800
  18. 1200
  19. 2400
  20. 1400
  21. 700
  22. 4000
  23. 1400
  24. 1400
  25. 600
  26. 800
  27. 2800
  28. 1400
  29. 4800
  30. 1200
  31. 800
  32. 8000
  33. 400
  34. 1200
  35. 1800
  36. 300
  37. 800
  38. 2700
  39. 400
  40. 800

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