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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 803 · 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 × 24? (a) 1600 (b) 160 (c) 16000
  2. 2.Best estimate of 16 × 98? (a) 2000 (b) 200 (c) 20000
  3. 3.Best estimate of 64 × 90? (a) 54000 (b) 540 (c) 5400
  4. 4.Best estimate of 616 + 348? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 19 × 62? (a) 1200 (b) 12000 (c) 120
  6. 6.Best estimate of 333 + 359? (a) 500 (b) 700 (c) 900
  7. 7.Best estimate of 225 + 344? (a) 500 (b) 700 (c) 300
  8. 8.Best estimate of 60 × 63? (a) 36000 (b) 3600 (c) 360
  9. 9.Best estimate of 69 × 13? (a) 700 (b) 70 (c) 7000
  10. 10.Best estimate of 27 × 78? (a) 2400 (b) 24000 (c) 240
  11. 11.Best estimate of 359 + 880? (a) 1300 (b) 1500 (c) 1100
  12. 12.Best estimate of 52 × 66? (a) 3500 (b) 350 (c) 35000
  13. 13.Best estimate of 188 + 140? (a) 300 (b) 100 (c) 500
  14. 14.Best estimate of 68 × 66? (a) 4900 (b) 490 (c) 49000
  15. 15.Best estimate of 88 × 46? (a) 450 (b) 45000 (c) 4500
  16. 16.Best estimate of 78 × 16? (a) 1600 (b) 160 (c) 16000
  17. 17.Best estimate of 479 + 825? (a) 1100 (b) 1500 (c) 1300
  18. 18.Best estimate of 26 × 34? (a) 90 (b) 9000 (c) 900
  19. 19.Best estimate of 338 + 165? (a) 700 (b) 300 (c) 500
  20. 20.Best estimate of 12 × 86? (a) 90 (b) 9000 (c) 900
  21. 21.Best estimate of 97 × 51? (a) 500 (b) 5000 (c) 50000
  22. 22.Best estimate of 40 × 74? (a) 280 (b) 28000 (c) 2800
  23. 23.Best estimate of 484 + 219? (a) 500 (b) 700 (c) 900
  24. 24.Best estimate of 800 + 127? (a) 900 (b) 1100 (c) 700
  25. 25.Best estimate of 36 × 31? (a) 1200 (b) 120 (c) 12000
  26. 26.Best estimate of 40 × 20? (a) 800 (b) 8000 (c) 80
  27. 27.Best estimate of 26 × 96? (a) 300 (b) 30000 (c) 3000
  28. 28.Best estimate of 479 + 864? (a) 1400 (b) 1200 (c) 1600
  29. 29.Best estimate of 51 × 39? (a) 20000 (b) 2000 (c) 200
  30. 30.Best estimate of 556 + 258? (a) 900 (b) 1100 (c) 700
  31. 31.Best estimate of 56 × 76? (a) 480 (b) 4800 (c) 48000
  32. 32.Best estimate of 158 + 274? (a) 500 (b) 700 (c) 300
  33. 33.Best estimate of 76 × 93? (a) 7200 (b) 720 (c) 72000
  34. 34.Best estimate of 32 × 80? (a) 240 (b) 2400 (c) 24000
  35. 35.Best estimate of 745 + 805? (a) 1700 (b) 1500 (c) 1300
  36. 36.Best estimate of 44 × 43? (a) 1600 (b) 160 (c) 16000
  37. 37.Best estimate of 790 + 196? (a) 1200 (b) 1000 (c) 800
  38. 38.Best estimate of 760 + 479? (a) 1500 (b) 1100 (c) 1300
  39. 39.Best estimate of 78 × 86? (a) 7200 (b) 720 (c) 72000
  40. 40.Best estimate of 445 + 429? (a) 800 (b) 1000 (c) 600

Answer key

  1. 1600
  2. 2000
  3. 5400
  4. 900
  5. 1200
  6. 700
  7. 500
  8. 3600
  9. 700
  10. 2400
  11. 1300
  12. 3500
  13. 300
  14. 4900
  15. 4500
  16. 1600
  17. 1300
  18. 900
  19. 500
  20. 900
  21. 5000
  22. 2800
  23. 700
  24. 900
  25. 1200
  26. 800
  27. 3000
  28. 1400
  29. 2000
  30. 900
  31. 4800
  32. 500
  33. 7200
  34. 2400
  35. 1500
  36. 1600
  37. 1000
  38. 1300
  39. 7200
  40. 800

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