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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 131 · 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 61 × 19? (a) 1200 (b) 12000 (c) 120
  2. 2.Best estimate of 300 + 874? (a) 1200 (b) 1400 (c) 1000
  3. 3.Best estimate of 318 + 634? (a) 700 (b) 900 (c) 1100
  4. 4.Best estimate of 604 + 547? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 26 × 98? (a) 30000 (b) 300 (c) 3000
  6. 6.Best estimate of 635 + 237? (a) 800 (b) 1000 (c) 600
  7. 7.Best estimate of 56 × 33? (a) 18000 (b) 180 (c) 1800
  8. 8.Best estimate of 496 + 381? (a) 1100 (b) 900 (c) 700
  9. 9.Best estimate of 481 + 854? (a) 1400 (b) 1200 (c) 1600
  10. 10.Best estimate of 76 × 80? (a) 64000 (b) 6400 (c) 640
  11. 11.Best estimate of 637 + 635? (a) 1400 (b) 1000 (c) 1200
  12. 12.Best estimate of 160 + 281? (a) 700 (b) 500 (c) 300
  13. 13.Best estimate of 92 × 67? (a) 6300 (b) 63000 (c) 630
  14. 14.Best estimate of 68 × 47? (a) 3500 (b) 35000 (c) 350
  15. 15.Best estimate of 848 + 817? (a) 1600 (b) 1400 (c) 1800
  16. 16.Best estimate of 500 + 721? (a) 1400 (b) 1000 (c) 1200
  17. 17.Best estimate of 23 × 81? (a) 16000 (b) 160 (c) 1600
  18. 18.Best estimate of 61 × 36? (a) 24000 (b) 2400 (c) 240
  19. 19.Best estimate of 60 × 27? (a) 18000 (b) 1800 (c) 180
  20. 20.Best estimate of 92 × 76? (a) 72000 (b) 7200 (c) 720
  21. 21.Best estimate of 32 × 76? (a) 2400 (b) 24000 (c) 240
  22. 22.Best estimate of 770 + 830? (a) 1800 (b) 1600 (c) 1400
  23. 23.Best estimate of 57 × 83? (a) 48000 (b) 4800 (c) 480
  24. 24.Best estimate of 13 × 42? (a) 40 (b) 400 (c) 4000
  25. 25.Best estimate of 20 × 71? (a) 1400 (b) 14000 (c) 140
  26. 26.Best estimate of 34 × 14? (a) 3000 (b) 300 (c) 30
  27. 27.Best estimate of 58 × 52? (a) 30000 (b) 3000 (c) 300
  28. 28.Best estimate of 704 + 835? (a) 1500 (b) 1700 (c) 1300
  29. 29.Best estimate of 32 × 83? (a) 2400 (b) 24000 (c) 240
  30. 30.Best estimate of 852 + 702? (a) 1800 (b) 1600 (c) 1400
  31. 31.Best estimate of 495 + 589? (a) 1300 (b) 1100 (c) 900
  32. 32.Best estimate of 140 + 677? (a) 600 (b) 800 (c) 1000
  33. 33.Best estimate of 96 × 41? (a) 40000 (b) 4000 (c) 400
  34. 34.Best estimate of 246 + 442? (a) 600 (b) 400 (c) 800
  35. 35.Best estimate of 82 × 40? (a) 3200 (b) 32000 (c) 320
  36. 36.Best estimate of 140 + 275? (a) 600 (b) 200 (c) 400
  37. 37.Best estimate of 68 × 71? (a) 490 (b) 4900 (c) 49000
  38. 38.Best estimate of 853 + 595? (a) 1700 (b) 1300 (c) 1500
  39. 39.Best estimate of 59 × 16? (a) 120 (b) 1200 (c) 12000
  40. 40.Best estimate of 239 + 394? (a) 800 (b) 400 (c) 600

Answer key

  1. 1200
  2. 1200
  3. 900
  4. 1100
  5. 3000
  6. 800
  7. 1800
  8. 900
  9. 1400
  10. 6400
  11. 1200
  12. 500
  13. 6300
  14. 3500
  15. 1600
  16. 1200
  17. 1600
  18. 2400
  19. 1800
  20. 7200
  21. 2400
  22. 1600
  23. 4800
  24. 400
  25. 1400
  26. 300
  27. 3000
  28. 1500
  29. 2400
  30. 1600
  31. 1100
  32. 800
  33. 4000
  34. 600
  35. 3200
  36. 400
  37. 4900
  38. 1500
  39. 1200
  40. 600

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