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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 61 · 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 260 + 586? (a) 1100 (b) 700 (c) 900
  2. 2.Best estimate of 19 × 66? (a) 1400 (b) 14000 (c) 140
  3. 3.Best estimate of 608 + 419? (a) 800 (b) 1000 (c) 1200
  4. 4.Best estimate of 88 × 28? (a) 270 (b) 2700 (c) 27000
  5. 5.Best estimate of 90 × 71? (a) 6300 (b) 63000 (c) 630
  6. 6.Best estimate of 33 × 80? (a) 24000 (b) 240 (c) 2400
  7. 7.Best estimate of 212 + 207? (a) 200 (b) 600 (c) 400
  8. 8.Best estimate of 734 + 127? (a) 600 (b) 1000 (c) 800
  9. 9.Best estimate of 66 × 97? (a) 70000 (b) 7000 (c) 700
  10. 10.Best estimate of 74 × 31? (a) 2100 (b) 210 (c) 21000
  11. 11.Best estimate of 38 × 23? (a) 8000 (b) 80 (c) 800
  12. 12.Best estimate of 668 + 476? (a) 1000 (b) 1400 (c) 1200
  13. 13.Best estimate of 17 × 92? (a) 180 (b) 1800 (c) 18000
  14. 14.Best estimate of 94 × 62? (a) 540 (b) 5400 (c) 54000
  15. 15.Best estimate of 388 + 708? (a) 1300 (b) 900 (c) 1100
  16. 16.Best estimate of 24 × 52? (a) 1000 (b) 10000 (c) 100
  17. 17.Best estimate of 27 × 91? (a) 270 (b) 2700 (c) 27000
  18. 18.Best estimate of 237 + 332? (a) 300 (b) 500 (c) 700
  19. 19.Best estimate of 325 + 390? (a) 900 (b) 700 (c) 500
  20. 20.Best estimate of 765 + 840? (a) 1600 (b) 1800 (c) 1400
  21. 21.Best estimate of 83 × 17? (a) 1600 (b) 160 (c) 16000
  22. 22.Best estimate of 517 + 807? (a) 1500 (b) 1100 (c) 1300
  23. 23.Best estimate of 83 × 86? (a) 72000 (b) 7200 (c) 720
  24. 24.Best estimate of 236 + 136? (a) 300 (b) 100 (c) 500
  25. 25.Best estimate of 129 + 862? (a) 1200 (b) 800 (c) 1000
  26. 26.Best estimate of 64 × 86? (a) 540 (b) 5400 (c) 54000
  27. 27.Best estimate of 28 × 76? (a) 240 (b) 24000 (c) 2400
  28. 28.Best estimate of 63 × 69? (a) 420 (b) 4200 (c) 42000
  29. 29.Best estimate of 513 + 201? (a) 700 (b) 500 (c) 900
  30. 30.Best estimate of 181 + 688? (a) 700 (b) 900 (c) 1100
  31. 31.Best estimate of 567 + 778? (a) 1400 (b) 1200 (c) 1600
  32. 32.Best estimate of 368 + 425? (a) 600 (b) 800 (c) 1000
  33. 33.Best estimate of 87 × 53? (a) 45000 (b) 4500 (c) 450
  34. 34.Best estimate of 307 + 464? (a) 1000 (b) 800 (c) 600
  35. 35.Best estimate of 844 + 197? (a) 800 (b) 1000 (c) 1200
  36. 36.Best estimate of 670 + 292? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 33 × 22? (a) 60 (b) 600 (c) 6000
  38. 38.Best estimate of 718 + 179? (a) 900 (b) 1100 (c) 700
  39. 39.Best estimate of 42 × 14? (a) 400 (b) 4000 (c) 40
  40. 40.Best estimate of 98 × 43? (a) 4000 (b) 400 (c) 40000

Answer key

  1. 900
  2. 1400
  3. 1000
  4. 2700
  5. 6300
  6. 2400
  7. 400
  8. 800
  9. 7000
  10. 2100
  11. 800
  12. 1200
  13. 1800
  14. 5400
  15. 1100
  16. 1000
  17. 2700
  18. 500
  19. 700
  20. 1600
  21. 1600
  22. 1300
  23. 7200
  24. 300
  25. 1000
  26. 5400
  27. 2400
  28. 4200
  29. 700
  30. 900
  31. 1400
  32. 800
  33. 4500
  34. 800
  35. 1000
  36. 1000
  37. 600
  38. 900
  39. 400
  40. 4000

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