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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 83 · 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 51 × 91? (a) 45000 (b) 450 (c) 4500
  2. 2.Best estimate of 532 + 389? (a) 700 (b) 1100 (c) 900
  3. 3.Best estimate of 24 × 37? (a) 8000 (b) 800 (c) 80
  4. 4.Best estimate of 479 + 449? (a) 900 (b) 700 (c) 1100
  5. 5.Best estimate of 88 × 73? (a) 630 (b) 63000 (c) 6300
  6. 6.Best estimate of 380 + 176? (a) 800 (b) 400 (c) 600
  7. 7.Best estimate of 496 + 608? (a) 1300 (b) 1100 (c) 900
  8. 8.Best estimate of 370 + 775? (a) 1000 (b) 1200 (c) 1400
  9. 9.Best estimate of 18 × 69? (a) 140 (b) 1400 (c) 14000
  10. 10.Best estimate of 348 + 832? (a) 1300 (b) 900 (c) 1100
  11. 11.Best estimate of 78 × 37? (a) 3200 (b) 32000 (c) 320
  12. 12.Best estimate of 640 + 644? (a) 1200 (b) 1400 (c) 1000
  13. 13.Best estimate of 77 × 97? (a) 80000 (b) 800 (c) 8000
  14. 14.Best estimate of 98 × 60? (a) 6000 (b) 60000 (c) 600
  15. 15.Best estimate of 51 × 67? (a) 3500 (b) 350 (c) 35000
  16. 16.Best estimate of 847 + 161? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 29 × 31? (a) 900 (b) 90 (c) 9000
  18. 18.Best estimate of 22 × 42? (a) 80 (b) 800 (c) 8000
  19. 19.Best estimate of 70 × 71? (a) 49000 (b) 4900 (c) 490
  20. 20.Best estimate of 610 + 209? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 24 × 26? (a) 60 (b) 600 (c) 6000
  22. 22.Best estimate of 24 × 33? (a) 600 (b) 6000 (c) 60
  23. 23.Best estimate of 539 + 874? (a) 1400 (b) 1200 (c) 1600
  24. 24.Best estimate of 263 + 722? (a) 1200 (b) 1000 (c) 800
  25. 25.Best estimate of 73 × 30? (a) 210 (b) 2100 (c) 21000
  26. 26.Best estimate of 747 + 352? (a) 1300 (b) 900 (c) 1100
  27. 27.Best estimate of 26 × 71? (a) 2100 (b) 210 (c) 21000
  28. 28.Best estimate of 17 × 87? (a) 18000 (b) 180 (c) 1800
  29. 29.Best estimate of 50 × 84? (a) 400 (b) 40000 (c) 4000
  30. 30.Best estimate of 625 + 126? (a) 900 (b) 500 (c) 700
  31. 31.Best estimate of 452 + 745? (a) 1200 (b) 1400 (c) 1000
  32. 32.Best estimate of 423 + 773? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 858 + 643? (a) 1500 (b) 1300 (c) 1700
  34. 34.Best estimate of 76 × 47? (a) 4000 (b) 40000 (c) 400
  35. 35.Best estimate of 234 + 345? (a) 700 (b) 300 (c) 500
  36. 36.Best estimate of 46 × 58? (a) 300 (b) 3000 (c) 30000
  37. 37.Best estimate of 415 + 286? (a) 900 (b) 700 (c) 500
  38. 38.Best estimate of 77 × 68? (a) 5600 (b) 56000 (c) 560
  39. 39.Best estimate of 87 × 52? (a) 4500 (b) 450 (c) 45000
  40. 40.Best estimate of 51 × 30? (a) 1500 (b) 15000 (c) 150

Answer key

  1. 4500
  2. 900
  3. 800
  4. 900
  5. 6300
  6. 600
  7. 1100
  8. 1200
  9. 1400
  10. 1100
  11. 3200
  12. 1200
  13. 8000
  14. 6000
  15. 3500
  16. 1000
  17. 900
  18. 800
  19. 4900
  20. 800
  21. 600
  22. 600
  23. 1400
  24. 1000
  25. 2100
  26. 1100
  27. 2100
  28. 1800
  29. 4000
  30. 700
  31. 1200
  32. 1200
  33. 1500
  34. 4000
  35. 500
  36. 3000
  37. 700
  38. 5600
  39. 4500
  40. 1500

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