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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 18 · 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 81 × 59? (a) 4800 (b) 48000 (c) 480
  2. 2.Best estimate of 513 + 563? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 87 × 38? (a) 36000 (b) 3600 (c) 360
  4. 4.Best estimate of 195 + 445? (a) 600 (b) 800 (c) 400
  5. 5.Best estimate of 77 × 71? (a) 56000 (b) 560 (c) 5600
  6. 6.Best estimate of 203 + 651? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 96 × 67? (a) 70000 (b) 7000 (c) 700
  8. 8.Best estimate of 304 + 249? (a) 500 (b) 300 (c) 700
  9. 9.Best estimate of 83 × 28? (a) 240 (b) 24000 (c) 2400
  10. 10.Best estimate of 23 × 67? (a) 1400 (b) 14000 (c) 140
  11. 11.Best estimate of 842 + 154? (a) 1200 (b) 800 (c) 1000
  12. 12.Best estimate of 36 × 74? (a) 280 (b) 2800 (c) 28000
  13. 13.Best estimate of 438 + 449? (a) 600 (b) 1000 (c) 800
  14. 14.Best estimate of 249 + 493? (a) 900 (b) 500 (c) 700
  15. 15.Best estimate of 771 + 220? (a) 1200 (b) 1000 (c) 800
  16. 16.Best estimate of 503 + 270? (a) 1000 (b) 600 (c) 800
  17. 17.Best estimate of 400 + 558? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 632 + 252? (a) 900 (b) 700 (c) 1100
  19. 19.Best estimate of 98 × 24? (a) 2000 (b) 200 (c) 20000
  20. 20.Best estimate of 256 + 304? (a) 600 (b) 400 (c) 800
  21. 21.Best estimate of 433 + 317? (a) 900 (b) 500 (c) 700
  22. 22.Best estimate of 37 × 31? (a) 1200 (b) 120 (c) 12000
  23. 23.Best estimate of 84 × 42? (a) 3200 (b) 32000 (c) 320
  24. 24.Best estimate of 63 × 24? (a) 120 (b) 1200 (c) 12000
  25. 25.Best estimate of 46 × 49? (a) 25000 (b) 2500 (c) 250
  26. 26.Best estimate of 14 × 19? (a) 20 (b) 200 (c) 2000
  27. 27.Best estimate of 48 × 66? (a) 35000 (b) 3500 (c) 350
  28. 28.Best estimate of 77 × 87? (a) 7200 (b) 72000 (c) 720
  29. 29.Best estimate of 94 × 59? (a) 54000 (b) 5400 (c) 540
  30. 30.Best estimate of 32 × 41? (a) 12000 (b) 120 (c) 1200
  31. 31.Best estimate of 67 × 76? (a) 5600 (b) 56000 (c) 560
  32. 32.Best estimate of 154 + 438? (a) 400 (b) 600 (c) 800
  33. 33.Best estimate of 96 × 56? (a) 60000 (b) 6000 (c) 600
  34. 34.Best estimate of 43 × 86? (a) 3600 (b) 36000 (c) 360
  35. 35.Best estimate of 49 × 53? (a) 2500 (b) 25000 (c) 250
  36. 36.Best estimate of 92 × 36? (a) 36000 (b) 3600 (c) 360
  37. 37.Best estimate of 553 + 663? (a) 1100 (b) 1300 (c) 1500
  38. 38.Best estimate of 66 × 41? (a) 2800 (b) 280 (c) 28000
  39. 39.Best estimate of 96 × 71? (a) 7000 (b) 700 (c) 70000
  40. 40.Best estimate of 701 + 295? (a) 1000 (b) 800 (c) 1200

Answer key

  1. 4800
  2. 1100
  3. 3600
  4. 600
  5. 5600
  6. 900
  7. 7000
  8. 500
  9. 2400
  10. 1400
  11. 1000
  12. 2800
  13. 800
  14. 700
  15. 1000
  16. 800
  17. 1000
  18. 900
  19. 2000
  20. 600
  21. 700
  22. 1200
  23. 3200
  24. 1200
  25. 2500
  26. 200
  27. 3500
  28. 7200
  29. 5400
  30. 1200
  31. 5600
  32. 600
  33. 6000
  34. 3600
  35. 2500
  36. 3600
  37. 1300
  38. 2800
  39. 7000
  40. 1000

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