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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 463 · 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 640 + 609? (a) 1000 (b) 1200 (c) 1400
  2. 2.Best estimate of 40 × 57? (a) 240 (b) 2400 (c) 24000
  3. 3.Best estimate of 61 × 51? (a) 30000 (b) 300 (c) 3000
  4. 4.Best estimate of 12 × 81? (a) 800 (b) 8000 (c) 80
  5. 5.Best estimate of 592 + 523? (a) 900 (b) 1100 (c) 1300
  6. 6.Best estimate of 36 × 21? (a) 8000 (b) 800 (c) 80
  7. 7.Best estimate of 44 × 46? (a) 20000 (b) 2000 (c) 200
  8. 8.Best estimate of 840 + 248? (a) 800 (b) 1200 (c) 1000
  9. 9.Best estimate of 596 + 126? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 21 × 84? (a) 1600 (b) 160 (c) 16000
  11. 11.Best estimate of 126 + 753? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 815 + 195? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 472 + 710? (a) 1200 (b) 1400 (c) 1000
  14. 14.Best estimate of 72 × 27? (a) 21000 (b) 210 (c) 2100
  15. 15.Best estimate of 32 × 78? (a) 2400 (b) 24000 (c) 240
  16. 16.Best estimate of 60 × 90? (a) 540 (b) 54000 (c) 5400
  17. 17.Best estimate of 816 + 386? (a) 1000 (b) 1200 (c) 1400
  18. 18.Best estimate of 29 × 29? (a) 90 (b) 9000 (c) 900
  19. 19.Best estimate of 146 + 723? (a) 800 (b) 600 (c) 1000
  20. 20.Best estimate of 326 + 853? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 570 + 634? (a) 1400 (b) 1000 (c) 1200
  22. 22.Best estimate of 24 × 79? (a) 16000 (b) 1600 (c) 160
  23. 23.Best estimate of 83 × 94? (a) 72000 (b) 720 (c) 7200
  24. 24.Best estimate of 79 × 23? (a) 1600 (b) 160 (c) 16000
  25. 25.Best estimate of 546 + 830? (a) 1300 (b) 1500 (c) 1100
  26. 26.Best estimate of 16 × 71? (a) 1400 (b) 14000 (c) 140
  27. 27.Best estimate of 86 × 51? (a) 4500 (b) 450 (c) 45000
  28. 28.Best estimate of 43 × 58? (a) 24000 (b) 240 (c) 2400
  29. 29.Best estimate of 77 × 67? (a) 560 (b) 5600 (c) 56000
  30. 30.Best estimate of 474 + 197? (a) 500 (b) 700 (c) 900
  31. 31.Best estimate of 67 × 86? (a) 630 (b) 63000 (c) 6300
  32. 32.Best estimate of 49 × 91? (a) 45000 (b) 450 (c) 4500
  33. 33.Best estimate of 430 + 825? (a) 1400 (b) 1200 (c) 1000
  34. 34.Best estimate of 98 × 30? (a) 3000 (b) 30000 (c) 300
  35. 35.Best estimate of 18 × 74? (a) 1400 (b) 14000 (c) 140
  36. 36.Best estimate of 352 + 678? (a) 900 (b) 1300 (c) 1100
  37. 37.Best estimate of 61 × 16? (a) 1200 (b) 120 (c) 12000
  38. 38.Best estimate of 50 × 52? (a) 2500 (b) 250 (c) 25000
  39. 39.Best estimate of 600 + 778? (a) 1600 (b) 1200 (c) 1400
  40. 40.Best estimate of 28 × 43? (a) 1200 (b) 120 (c) 12000

Answer key

  1. 1200
  2. 2400
  3. 3000
  4. 800
  5. 1100
  6. 800
  7. 2000
  8. 1000
  9. 700
  10. 1600
  11. 900
  12. 1000
  13. 1200
  14. 2100
  15. 2400
  16. 5400
  17. 1200
  18. 900
  19. 800
  20. 1200
  21. 1200
  22. 1600
  23. 7200
  24. 1600
  25. 1300
  26. 1400
  27. 4500
  28. 2400
  29. 5600
  30. 700
  31. 6300
  32. 4500
  33. 1200
  34. 3000
  35. 1400
  36. 1100
  37. 1200
  38. 2500
  39. 1400
  40. 1200

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