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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 626 · 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 285 + 312? (a) 600 (b) 400 (c) 800
  2. 2.Best estimate of 89 × 22? (a) 1800 (b) 180 (c) 18000
  3. 3.Best estimate of 20 × 57? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 23 × 42? (a) 8000 (b) 800 (c) 80
  5. 5.Best estimate of 59 × 63? (a) 36000 (b) 360 (c) 3600
  6. 6.Best estimate of 848 + 695? (a) 1500 (b) 1300 (c) 1700
  7. 7.Best estimate of 80 × 63? (a) 48000 (b) 480 (c) 4800
  8. 8.Best estimate of 18 × 42? (a) 800 (b) 8000 (c) 80
  9. 9.Best estimate of 14 × 80? (a) 800 (b) 8000 (c) 80
  10. 10.Best estimate of 42 × 46? (a) 20000 (b) 2000 (c) 200
  11. 11.Best estimate of 297 + 639? (a) 1100 (b) 700 (c) 900
  12. 12.Best estimate of 247 + 781? (a) 800 (b) 1200 (c) 1000
  13. 13.Best estimate of 433 + 589? (a) 1200 (b) 800 (c) 1000
  14. 14.Best estimate of 533 + 201? (a) 700 (b) 500 (c) 900
  15. 15.Best estimate of 33 × 53? (a) 1500 (b) 15000 (c) 150
  16. 16.Best estimate of 41 × 92? (a) 3600 (b) 36000 (c) 360
  17. 17.Best estimate of 86 × 14? (a) 90 (b) 9000 (c) 900
  18. 18.Best estimate of 494 + 555? (a) 900 (b) 1100 (c) 1300
  19. 19.Best estimate of 875 + 364? (a) 1500 (b) 1300 (c) 1100
  20. 20.Best estimate of 16 × 84? (a) 160 (b) 16000 (c) 1600
  21. 21.Best estimate of 72 × 44? (a) 280 (b) 2800 (c) 28000
  22. 22.Best estimate of 523 + 326? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 21 × 83? (a) 1600 (b) 160 (c) 16000
  24. 24.Best estimate of 84 × 96? (a) 8000 (b) 800 (c) 80000
  25. 25.Best estimate of 27 × 52? (a) 1500 (b) 15000 (c) 150
  26. 26.Best estimate of 50 × 21? (a) 1000 (b) 100 (c) 10000
  27. 27.Best estimate of 572 + 219? (a) 600 (b) 800 (c) 1000
  28. 28.Best estimate of 76 × 34? (a) 240 (b) 2400 (c) 24000
  29. 29.Best estimate of 96 × 46? (a) 500 (b) 50000 (c) 5000
  30. 30.Best estimate of 860 + 182? (a) 1100 (b) 1300 (c) 900
  31. 31.Best estimate of 96 × 43? (a) 400 (b) 4000 (c) 40000
  32. 32.Best estimate of 237 + 389? (a) 600 (b) 800 (c) 400
  33. 33.Best estimate of 86 × 53? (a) 45000 (b) 4500 (c) 450
  34. 34.Best estimate of 58 × 59? (a) 360 (b) 3600 (c) 36000
  35. 35.Best estimate of 565 + 545? (a) 1300 (b) 900 (c) 1100
  36. 36.Best estimate of 733 + 183? (a) 1100 (b) 900 (c) 700
  37. 37.Best estimate of 456 + 532? (a) 800 (b) 1000 (c) 1200
  38. 38.Best estimate of 33 × 36? (a) 1200 (b) 120 (c) 12000
  39. 39.Best estimate of 879 + 610? (a) 1300 (b) 1500 (c) 1700
  40. 40.Best estimate of 96 × 58? (a) 600 (b) 60000 (c) 6000

Answer key

  1. 600
  2. 1800
  3. 1200
  4. 800
  5. 3600
  6. 1500
  7. 4800
  8. 800
  9. 800
  10. 2000
  11. 900
  12. 1000
  13. 1000
  14. 700
  15. 1500
  16. 3600
  17. 900
  18. 1100
  19. 1300
  20. 1600
  21. 2800
  22. 800
  23. 1600
  24. 8000
  25. 1500
  26. 1000
  27. 800
  28. 2400
  29. 5000
  30. 1100
  31. 4000
  32. 600
  33. 4500
  34. 3600
  35. 1100
  36. 900
  37. 1000
  38. 1200
  39. 1500
  40. 6000

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