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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 390 · 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 874 + 786? (a) 1700 (b) 1900 (c) 1500
  2. 2.Best estimate of 612 + 622? (a) 1000 (b) 1400 (c) 1200
  3. 3.Best estimate of 61 × 16? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 30 × 26? (a) 9000 (b) 90 (c) 900
  5. 5.Best estimate of 50 × 34? (a) 1500 (b) 150 (c) 15000
  6. 6.Best estimate of 84 × 79? (a) 6400 (b) 64000 (c) 640
  7. 7.Best estimate of 340 + 805? (a) 900 (b) 1300 (c) 1100
  8. 8.Best estimate of 225 + 248? (a) 200 (b) 600 (c) 400
  9. 9.Best estimate of 216 + 321? (a) 700 (b) 500 (c) 300
  10. 10.Best estimate of 92 × 81? (a) 7200 (b) 72000 (c) 720
  11. 11.Best estimate of 432 + 135? (a) 500 (b) 300 (c) 700
  12. 12.Best estimate of 584 + 731? (a) 1300 (b) 1100 (c) 1500
  13. 13.Best estimate of 56 × 90? (a) 54000 (b) 540 (c) 5400
  14. 14.Best estimate of 77 × 32? (a) 2400 (b) 240 (c) 24000
  15. 15.Best estimate of 523 + 706? (a) 1400 (b) 1000 (c) 1200
  16. 16.Best estimate of 864 + 547? (a) 1200 (b) 1400 (c) 1600
  17. 17.Best estimate of 90 × 83? (a) 7200 (b) 720 (c) 72000
  18. 18.Best estimate of 96 × 44? (a) 400 (b) 40000 (c) 4000
  19. 19.Best estimate of 300 + 362? (a) 500 (b) 700 (c) 900
  20. 20.Best estimate of 612 + 215? (a) 600 (b) 1000 (c) 800
  21. 21.Best estimate of 599 + 266? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 299 + 189? (a) 700 (b) 500 (c) 300
  23. 23.Best estimate of 47 × 39? (a) 20000 (b) 200 (c) 2000
  24. 24.Best estimate of 516 + 645? (a) 900 (b) 1100 (c) 1300
  25. 25.Best estimate of 91 × 71? (a) 63000 (b) 6300 (c) 630
  26. 26.Best estimate of 94 × 74? (a) 6300 (b) 630 (c) 63000
  27. 27.Best estimate of 60 × 83? (a) 48000 (b) 4800 (c) 480
  28. 28.Best estimate of 46 × 16? (a) 1000 (b) 10000 (c) 100
  29. 29.Best estimate of 22 × 19? (a) 400 (b) 4000 (c) 40
  30. 30.Best estimate of 46 × 17? (a) 1000 (b) 10000 (c) 100
  31. 31.Best estimate of 316 + 339? (a) 400 (b) 800 (c) 600
  32. 32.Best estimate of 13 × 66? (a) 70 (b) 700 (c) 7000
  33. 33.Best estimate of 318 + 321? (a) 400 (b) 800 (c) 600
  34. 34.Best estimate of 58 × 59? (a) 3600 (b) 36000 (c) 360
  35. 35.Best estimate of 84 × 16? (a) 1600 (b) 160 (c) 16000
  36. 36.Best estimate of 44 × 48? (a) 2000 (b) 200 (c) 20000
  37. 37.Best estimate of 68 × 63? (a) 42000 (b) 4200 (c) 420
  38. 38.Best estimate of 456 + 755? (a) 1300 (b) 1500 (c) 1100
  39. 39.Best estimate of 735 + 644? (a) 1500 (b) 1100 (c) 1300
  40. 40.Best estimate of 404 + 637? (a) 800 (b) 1200 (c) 1000

Answer key

  1. 1700
  2. 1200
  3. 1200
  4. 900
  5. 1500
  6. 6400
  7. 1100
  8. 400
  9. 500
  10. 7200
  11. 500
  12. 1300
  13. 5400
  14. 2400
  15. 1200
  16. 1400
  17. 7200
  18. 4000
  19. 700
  20. 800
  21. 900
  22. 500
  23. 2000
  24. 1100
  25. 6300
  26. 6300
  27. 4800
  28. 1000
  29. 400
  30. 1000
  31. 600
  32. 700
  33. 600
  34. 3600
  35. 1600
  36. 2000
  37. 4200
  38. 1300
  39. 1300
  40. 1000

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