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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 92 · 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 584 + 790? (a) 1200 (b) 1600 (c) 1400
  2. 2.Best estimate of 674 + 221? (a) 1100 (b) 900 (c) 700
  3. 3.Best estimate of 220 + 789? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 344 + 159? (a) 500 (b) 300 (c) 700
  5. 5.Best estimate of 27 × 20? (a) 6000 (b) 600 (c) 60
  6. 6.Best estimate of 646 + 464? (a) 900 (b) 1300 (c) 1100
  7. 7.Best estimate of 86 × 84? (a) 72000 (b) 720 (c) 7200
  8. 8.Best estimate of 326 + 802? (a) 1100 (b) 900 (c) 1300
  9. 9.Best estimate of 88 × 96? (a) 900 (b) 9000 (c) 90000
  10. 10.Best estimate of 502 + 416? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 39 × 42? (a) 160 (b) 1600 (c) 16000
  12. 12.Best estimate of 51 × 37? (a) 20000 (b) 200 (c) 2000
  13. 13.Best estimate of 658 + 606? (a) 1500 (b) 1100 (c) 1300
  14. 14.Best estimate of 64 × 67? (a) 42000 (b) 420 (c) 4200
  15. 15.Best estimate of 397 + 380? (a) 800 (b) 600 (c) 1000
  16. 16.Best estimate of 66 × 42? (a) 28000 (b) 280 (c) 2800
  17. 17.Best estimate of 33 × 96? (a) 30000 (b) 3000 (c) 300
  18. 18.Best estimate of 70 × 33? (a) 210 (b) 21000 (c) 2100
  19. 19.Best estimate of 291 + 841? (a) 1300 (b) 900 (c) 1100
  20. 20.Best estimate of 493 + 579? (a) 900 (b) 1100 (c) 1300
  21. 21.Best estimate of 86 × 16? (a) 1800 (b) 180 (c) 18000
  22. 22.Best estimate of 92 × 51? (a) 45000 (b) 450 (c) 4500
  23. 23.Best estimate of 16 × 50? (a) 100 (b) 10000 (c) 1000
  24. 24.Best estimate of 22 × 77? (a) 1600 (b) 16000 (c) 160
  25. 25.Best estimate of 306 + 190? (a) 300 (b) 500 (c) 700
  26. 26.Best estimate of 91 × 69? (a) 63000 (b) 630 (c) 6300
  27. 27.Best estimate of 347 + 500? (a) 600 (b) 800 (c) 1000
  28. 28.Best estimate of 91 × 54? (a) 45000 (b) 4500 (c) 450
  29. 29.Best estimate of 20 × 74? (a) 1400 (b) 14000 (c) 140
  30. 30.Best estimate of 32 × 68? (a) 21000 (b) 2100 (c) 210
  31. 31.Best estimate of 13 × 78? (a) 80 (b) 8000 (c) 800
  32. 32.Best estimate of 87 × 74? (a) 63000 (b) 630 (c) 6300
  33. 33.Best estimate of 77 × 86? (a) 72000 (b) 7200 (c) 720
  34. 34.Best estimate of 180 + 266? (a) 300 (b) 500 (c) 700
  35. 35.Best estimate of 630 + 184? (a) 800 (b) 1000 (c) 600
  36. 36.Best estimate of 83 × 31? (a) 240 (b) 2400 (c) 24000
  37. 37.Best estimate of 506 + 664? (a) 1000 (b) 1400 (c) 1200
  38. 38.Best estimate of 56 × 31? (a) 18000 (b) 180 (c) 1800
  39. 39.Best estimate of 33 × 64? (a) 180 (b) 18000 (c) 1800
  40. 40.Best estimate of 88 × 84? (a) 720 (b) 7200 (c) 72000

Answer key

  1. 1400
  2. 900
  3. 1000
  4. 500
  5. 600
  6. 1100
  7. 7200
  8. 1100
  9. 9000
  10. 900
  11. 1600
  12. 2000
  13. 1300
  14. 4200
  15. 800
  16. 2800
  17. 3000
  18. 2100
  19. 1100
  20. 1100
  21. 1800
  22. 4500
  23. 1000
  24. 1600
  25. 500
  26. 6300
  27. 800
  28. 4500
  29. 1400
  30. 2100
  31. 800
  32. 6300
  33. 7200
  34. 500
  35. 800
  36. 2400
  37. 1200
  38. 1800
  39. 1800
  40. 7200

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