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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 782 · 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 24 × 37? (a) 8000 (b) 80 (c) 800
  2. 2.Best estimate of 49 × 47? (a) 2500 (b) 250 (c) 25000
  3. 3.Best estimate of 269 + 845? (a) 1300 (b) 1100 (c) 900
  4. 4.Best estimate of 48 × 86? (a) 450 (b) 45000 (c) 4500
  5. 5.Best estimate of 447 + 227? (a) 800 (b) 400 (c) 600
  6. 6.Best estimate of 89 × 26? (a) 27000 (b) 2700 (c) 270
  7. 7.Best estimate of 93 × 56? (a) 5400 (b) 54000 (c) 540
  8. 8.Best estimate of 28 × 29? (a) 90 (b) 9000 (c) 900
  9. 9.Best estimate of 56 × 28? (a) 1800 (b) 18000 (c) 180
  10. 10.Best estimate of 20 × 63? (a) 12000 (b) 1200 (c) 120
  11. 11.Best estimate of 576 + 155? (a) 800 (b) 1000 (c) 600
  12. 12.Best estimate of 700 + 721? (a) 1400 (b) 1600 (c) 1200
  13. 13.Best estimate of 26 × 48? (a) 150 (b) 15000 (c) 1500
  14. 14.Best estimate of 296 + 804? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 37 × 76? (a) 320 (b) 3200 (c) 32000
  16. 16.Best estimate of 76 × 16? (a) 1600 (b) 16000 (c) 160
  17. 17.Best estimate of 313 + 192? (a) 500 (b) 700 (c) 300
  18. 18.Best estimate of 645 + 259? (a) 1100 (b) 900 (c) 700
  19. 19.Best estimate of 176 + 223? (a) 200 (b) 400 (c) 600
  20. 20.Best estimate of 851 + 587? (a) 1700 (b) 1500 (c) 1300
  21. 21.Best estimate of 353 + 744? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 91 × 29? (a) 270 (b) 2700 (c) 27000
  23. 23.Best estimate of 33 × 16? (a) 600 (b) 6000 (c) 60
  24. 24.Best estimate of 79 × 68? (a) 560 (b) 5600 (c) 56000
  25. 25.Best estimate of 30 × 29? (a) 900 (b) 90 (c) 9000
  26. 26.Best estimate of 28 × 27? (a) 9000 (b) 900 (c) 90
  27. 27.Best estimate of 641 + 435? (a) 800 (b) 1200 (c) 1000
  28. 28.Best estimate of 235 + 721? (a) 1100 (b) 900 (c) 700
  29. 29.Best estimate of 49 × 64? (a) 3000 (b) 300 (c) 30000
  30. 30.Best estimate of 460 + 333? (a) 600 (b) 800 (c) 1000
  31. 31.Best estimate of 98 × 28? (a) 3000 (b) 300 (c) 30000
  32. 32.Best estimate of 768 + 714? (a) 1500 (b) 1300 (c) 1700
  33. 33.Best estimate of 54 × 20? (a) 1000 (b) 10000 (c) 100
  34. 34.Best estimate of 63 × 38? (a) 240 (b) 24000 (c) 2400
  35. 35.Best estimate of 496 + 846? (a) 1500 (b) 1100 (c) 1300
  36. 36.Best estimate of 79 × 61? (a) 480 (b) 48000 (c) 4800
  37. 37.Best estimate of 80 × 86? (a) 720 (b) 7200 (c) 72000
  38. 38.Best estimate of 90 × 29? (a) 270 (b) 27000 (c) 2700
  39. 39.Best estimate of 646 + 408? (a) 1000 (b) 800 (c) 1200
  40. 40.Best estimate of 26 × 20? (a) 6000 (b) 60 (c) 600

Answer key

  1. 800
  2. 2500
  3. 1100
  4. 4500
  5. 600
  6. 2700
  7. 5400
  8. 900
  9. 1800
  10. 1200
  11. 800
  12. 1400
  13. 1500
  14. 1100
  15. 3200
  16. 1600
  17. 500
  18. 900
  19. 400
  20. 1500
  21. 1100
  22. 2700
  23. 600
  24. 5600
  25. 900
  26. 900
  27. 1000
  28. 900
  29. 3000
  30. 800
  31. 3000
  32. 1500
  33. 1000
  34. 2400
  35. 1300
  36. 4800
  37. 7200
  38. 2700
  39. 1000
  40. 600

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