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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 926 · 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 83 × 87? (a) 72000 (b) 7200 (c) 720
  2. 2.Best estimate of 46 × 39? (a) 20000 (b) 2000 (c) 200
  3. 3.Best estimate of 689 + 867? (a) 1600 (b) 1400 (c) 1800
  4. 4.Best estimate of 67 × 59? (a) 4200 (b) 420 (c) 42000
  5. 5.Best estimate of 58 × 80? (a) 48000 (b) 480 (c) 4800
  6. 6.Best estimate of 285 + 624? (a) 1100 (b) 900 (c) 700
  7. 7.Best estimate of 44 × 60? (a) 240 (b) 24000 (c) 2400
  8. 8.Best estimate of 421 + 785? (a) 1400 (b) 1200 (c) 1000
  9. 9.Best estimate of 31 × 33? (a) 900 (b) 9000 (c) 90
  10. 10.Best estimate of 478 + 540? (a) 800 (b) 1000 (c) 1200
  11. 11.Best estimate of 27 × 24? (a) 6000 (b) 60 (c) 600
  12. 12.Best estimate of 41 × 81? (a) 3200 (b) 320 (c) 32000
  13. 13.Best estimate of 32 × 56? (a) 1800 (b) 180 (c) 18000
  14. 14.Best estimate of 51 × 28? (a) 1500 (b) 15000 (c) 150
  15. 15.Best estimate of 846 + 127? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 36 × 40? (a) 160 (b) 16000 (c) 1600
  17. 17.Best estimate of 24 × 33? (a) 60 (b) 600 (c) 6000
  18. 18.Best estimate of 460 + 295? (a) 800 (b) 1000 (c) 600
  19. 19.Best estimate of 41 × 59? (a) 2400 (b) 24000 (c) 240
  20. 20.Best estimate of 83 × 34? (a) 2400 (b) 24000 (c) 240
  21. 21.Best estimate of 644 + 579? (a) 1000 (b) 1200 (c) 1400
  22. 22.Best estimate of 61 × 12? (a) 60 (b) 6000 (c) 600
  23. 23.Best estimate of 19 × 13? (a) 2000 (b) 200 (c) 20
  24. 24.Best estimate of 694 + 792? (a) 1700 (b) 1500 (c) 1300
  25. 25.Best estimate of 58 × 74? (a) 4200 (b) 42000 (c) 420
  26. 26.Best estimate of 730 + 656? (a) 1600 (b) 1400 (c) 1200
  27. 27.Best estimate of 864 + 176? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 202 + 236? (a) 200 (b) 600 (c) 400
  29. 29.Best estimate of 704 + 399? (a) 1300 (b) 900 (c) 1100
  30. 30.Best estimate of 419 + 248? (a) 800 (b) 600 (c) 400
  31. 31.Best estimate of 16 × 72? (a) 1400 (b) 140 (c) 14000
  32. 32.Best estimate of 634 + 771? (a) 1400 (b) 1200 (c) 1600
  33. 33.Best estimate of 26 × 74? (a) 2100 (b) 210 (c) 21000
  34. 34.Best estimate of 26 × 63? (a) 18000 (b) 180 (c) 1800
  35. 35.Best estimate of 68 × 34? (a) 21000 (b) 210 (c) 2100
  36. 36.Best estimate of 51 × 69? (a) 35000 (b) 350 (c) 3500
  37. 37.Best estimate of 14 × 31? (a) 3000 (b) 300 (c) 30
  38. 38.Best estimate of 256 + 613? (a) 700 (b) 1100 (c) 900
  39. 39.Best estimate of 66 × 41? (a) 280 (b) 28000 (c) 2800
  40. 40.Best estimate of 26 × 36? (a) 12000 (b) 1200 (c) 120

Answer key

  1. 7200
  2. 2000
  3. 1600
  4. 4200
  5. 4800
  6. 900
  7. 2400
  8. 1200
  9. 900
  10. 1000
  11. 600
  12. 3200
  13. 1800
  14. 1500
  15. 900
  16. 1600
  17. 600
  18. 800
  19. 2400
  20. 2400
  21. 1200
  22. 600
  23. 200
  24. 1500
  25. 4200
  26. 1400
  27. 1100
  28. 400
  29. 1100
  30. 600
  31. 1400
  32. 1400
  33. 2100
  34. 1800
  35. 2100
  36. 3500
  37. 300
  38. 900
  39. 2800
  40. 1200

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