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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 554 · 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 16 × 61? (a) 120 (b) 12000 (c) 1200
  2. 2.Best estimate of 86 × 72? (a) 63000 (b) 6300 (c) 630
  3. 3.Best estimate of 225 + 520? (a) 700 (b) 900 (c) 500
  4. 4.Best estimate of 26 × 62? (a) 1800 (b) 18000 (c) 180
  5. 5.Best estimate of 12 × 14? (a) 1000 (b) 100 (c) 10
  6. 6.Best estimate of 20 × 88? (a) 1800 (b) 18000 (c) 180
  7. 7.Best estimate of 29 × 46? (a) 1500 (b) 15000 (c) 150
  8. 8.Best estimate of 157 + 507? (a) 500 (b) 700 (c) 900
  9. 9.Best estimate of 747 + 663? (a) 1600 (b) 1400 (c) 1200
  10. 10.Best estimate of 81 × 66? (a) 56000 (b) 5600 (c) 560
  11. 11.Best estimate of 289 + 319? (a) 400 (b) 800 (c) 600
  12. 12.Best estimate of 494 + 282? (a) 800 (b) 1000 (c) 600
  13. 13.Best estimate of 224 + 777? (a) 800 (b) 1200 (c) 1000
  14. 14.Best estimate of 874 + 753? (a) 1700 (b) 1500 (c) 1900
  15. 15.Best estimate of 277 + 245? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 275 + 554? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 246 + 431? (a) 600 (b) 400 (c) 800
  18. 18.Best estimate of 536 + 607? (a) 1100 (b) 900 (c) 1300
  19. 19.Best estimate of 538 + 280? (a) 600 (b) 800 (c) 1000
  20. 20.Best estimate of 24 × 49? (a) 10000 (b) 1000 (c) 100
  21. 21.Best estimate of 683 + 336? (a) 1200 (b) 1000 (c) 800
  22. 22.Best estimate of 522 + 749? (a) 1400 (b) 1200 (c) 1000
  23. 23.Best estimate of 64 × 77? (a) 48000 (b) 4800 (c) 480
  24. 24.Best estimate of 853 + 711? (a) 1400 (b) 1600 (c) 1800
  25. 25.Best estimate of 21 × 91? (a) 18000 (b) 1800 (c) 180
  26. 26.Best estimate of 559 + 769? (a) 1600 (b) 1200 (c) 1400
  27. 27.Best estimate of 288 + 805? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 398 + 749? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 19 × 26? (a) 6000 (b) 600 (c) 60
  30. 30.Best estimate of 351 + 763? (a) 1400 (b) 1000 (c) 1200
  31. 31.Best estimate of 533 + 335? (a) 600 (b) 800 (c) 1000
  32. 32.Best estimate of 315 + 697? (a) 800 (b) 1000 (c) 1200
  33. 33.Best estimate of 41 × 23? (a) 80 (b) 800 (c) 8000
  34. 34.Best estimate of 32 × 98? (a) 3000 (b) 300 (c) 30000
  35. 35.Best estimate of 29 × 69? (a) 210 (b) 2100 (c) 21000
  36. 36.Best estimate of 16 × 71? (a) 1400 (b) 14000 (c) 140
  37. 37.Best estimate of 78 × 66? (a) 560 (b) 56000 (c) 5600
  38. 38.Best estimate of 98 × 69? (a) 70000 (b) 7000 (c) 700
  39. 39.Best estimate of 96 × 47? (a) 5000 (b) 500 (c) 50000
  40. 40.Best estimate of 610 + 332? (a) 700 (b) 900 (c) 1100

Answer key

  1. 1200
  2. 6300
  3. 700
  4. 1800
  5. 100
  6. 1800
  7. 1500
  8. 700
  9. 1400
  10. 5600
  11. 600
  12. 800
  13. 1000
  14. 1700
  15. 500
  16. 900
  17. 600
  18. 1100
  19. 800
  20. 1000
  21. 1000
  22. 1200
  23. 4800
  24. 1600
  25. 1800
  26. 1400
  27. 1100
  28. 1100
  29. 600
  30. 1200
  31. 800
  32. 1000
  33. 800
  34. 3000
  35. 2100
  36. 1400
  37. 5600
  38. 7000
  39. 5000
  40. 900

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