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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 154 · 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 32 × 98? (a) 30000 (b) 3000 (c) 300
  2. 2.Best estimate of 96 × 74? (a) 70000 (b) 7000 (c) 700
  3. 3.Best estimate of 20 × 60? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 46 × 81? (a) 40000 (b) 4000 (c) 400
  5. 5.Best estimate of 275 + 577? (a) 700 (b) 900 (c) 1100
  6. 6.Best estimate of 14 × 80? (a) 8000 (b) 800 (c) 80
  7. 7.Best estimate of 384 + 700? (a) 900 (b) 1300 (c) 1100
  8. 8.Best estimate of 80 × 28? (a) 240 (b) 2400 (c) 24000
  9. 9.Best estimate of 790 + 219? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 97 × 77? (a) 8000 (b) 80000 (c) 800
  11. 11.Best estimate of 596 + 318? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 39 × 60? (a) 2400 (b) 240 (c) 24000
  13. 13.Best estimate of 58 × 82? (a) 480 (b) 4800 (c) 48000
  14. 14.Best estimate of 230 + 796? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 127 + 326? (a) 400 (b) 600 (c) 200
  16. 16.Best estimate of 143 + 251? (a) 600 (b) 400 (c) 200
  17. 17.Best estimate of 68 × 27? (a) 210 (b) 2100 (c) 21000
  18. 18.Best estimate of 23 × 67? (a) 140 (b) 14000 (c) 1400
  19. 19.Best estimate of 54 × 50? (a) 250 (b) 25000 (c) 2500
  20. 20.Best estimate of 39 × 67? (a) 28000 (b) 2800 (c) 280
  21. 21.Best estimate of 399 + 498? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 20 × 77? (a) 16000 (b) 1600 (c) 160
  23. 23.Best estimate of 635 + 231? (a) 1000 (b) 600 (c) 800
  24. 24.Best estimate of 16 × 32? (a) 6000 (b) 600 (c) 60
  25. 25.Best estimate of 90 × 29? (a) 27000 (b) 2700 (c) 270
  26. 26.Best estimate of 71 × 59? (a) 4200 (b) 42000 (c) 420
  27. 27.Best estimate of 13 × 86? (a) 900 (b) 9000 (c) 90
  28. 28.Best estimate of 47 × 12? (a) 50 (b) 5000 (c) 500
  29. 29.Best estimate of 44 × 20? (a) 80 (b) 8000 (c) 800
  30. 30.Best estimate of 81 × 79? (a) 6400 (b) 640 (c) 64000
  31. 31.Best estimate of 70 × 14? (a) 70 (b) 700 (c) 7000
  32. 32.Best estimate of 92 × 23? (a) 180 (b) 1800 (c) 18000
  33. 33.Best estimate of 751 + 308? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 41 × 98? (a) 400 (b) 4000 (c) 40000
  35. 35.Best estimate of 92 × 36? (a) 36000 (b) 3600 (c) 360
  36. 36.Best estimate of 231 + 564? (a) 800 (b) 600 (c) 1000
  37. 37.Best estimate of 380 + 422? (a) 1000 (b) 600 (c) 800
  38. 38.Best estimate of 20 × 83? (a) 16000 (b) 160 (c) 1600
  39. 39.Best estimate of 30 × 64? (a) 1800 (b) 18000 (c) 180
  40. 40.Best estimate of 224 + 653? (a) 900 (b) 1100 (c) 700

Answer key

  1. 3000
  2. 7000
  3. 1200
  4. 4000
  5. 900
  6. 800
  7. 1100
  8. 2400
  9. 1000
  10. 8000
  11. 900
  12. 2400
  13. 4800
  14. 1000
  15. 400
  16. 400
  17. 2100
  18. 1400
  19. 2500
  20. 2800
  21. 900
  22. 1600
  23. 800
  24. 600
  25. 2700
  26. 4200
  27. 900
  28. 500
  29. 800
  30. 6400
  31. 700
  32. 1800
  33. 1100
  34. 4000
  35. 3600
  36. 800
  37. 800
  38. 1600
  39. 1800
  40. 900

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