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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 671 · 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 91 × 52? (a) 45000 (b) 450 (c) 4500
  2. 2.Best estimate of 28 × 82? (a) 2400 (b) 24000 (c) 240
  3. 3.Best estimate of 531 + 781? (a) 1300 (b) 1500 (c) 1100
  4. 4.Best estimate of 490 + 249? (a) 700 (b) 500 (c) 900
  5. 5.Best estimate of 18 × 60? (a) 1200 (b) 12000 (c) 120
  6. 6.Best estimate of 141 + 277? (a) 600 (b) 200 (c) 400
  7. 7.Best estimate of 389 + 597? (a) 1200 (b) 1000 (c) 800
  8. 8.Best estimate of 48 × 50? (a) 25000 (b) 250 (c) 2500
  9. 9.Best estimate of 14 × 83? (a) 8000 (b) 800 (c) 80
  10. 10.Best estimate of 312 + 806? (a) 1100 (b) 1300 (c) 900
  11. 11.Best estimate of 128 + 457? (a) 800 (b) 600 (c) 400
  12. 12.Best estimate of 22 × 37? (a) 80 (b) 800 (c) 8000
  13. 13.Best estimate of 610 + 392? (a) 800 (b) 1000 (c) 1200
  14. 14.Best estimate of 46 × 28? (a) 1500 (b) 15000 (c) 150
  15. 15.Best estimate of 30 × 74? (a) 21000 (b) 210 (c) 2100
  16. 16.Best estimate of 268 + 178? (a) 500 (b) 300 (c) 700
  17. 17.Best estimate of 230 + 724? (a) 900 (b) 1100 (c) 700
  18. 18.Best estimate of 16 × 56? (a) 120 (b) 12000 (c) 1200
  19. 19.Best estimate of 133 + 531? (a) 600 (b) 800 (c) 400
  20. 20.Best estimate of 77 × 56? (a) 480 (b) 48000 (c) 4800
  21. 21.Best estimate of 863 + 428? (a) 1500 (b) 1100 (c) 1300
  22. 22.Best estimate of 34 × 24? (a) 6000 (b) 600 (c) 60
  23. 23.Best estimate of 335 + 622? (a) 900 (b) 700 (c) 1100
  24. 24.Best estimate of 386 + 472? (a) 1100 (b) 700 (c) 900
  25. 25.Best estimate of 24 × 36? (a) 800 (b) 8000 (c) 80
  26. 26.Best estimate of 123 + 303? (a) 600 (b) 400 (c) 200
  27. 27.Best estimate of 190 + 487? (a) 900 (b) 500 (c) 700
  28. 28.Best estimate of 817 + 197? (a) 1000 (b) 800 (c) 1200
  29. 29.Best estimate of 96 × 64? (a) 600 (b) 60000 (c) 6000
  30. 30.Best estimate of 90 × 97? (a) 9000 (b) 900 (c) 90000
  31. 31.Best estimate of 586 + 258? (a) 900 (b) 1100 (c) 700
  32. 32.Best estimate of 73 × 50? (a) 3500 (b) 35000 (c) 350
  33. 33.Best estimate of 16 × 59? (a) 12000 (b) 1200 (c) 120
  34. 34.Best estimate of 74 × 53? (a) 350 (b) 35000 (c) 3500
  35. 35.Best estimate of 33 × 26? (a) 90 (b) 9000 (c) 900
  36. 36.Best estimate of 26 × 84? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 13 × 18? (a) 200 (b) 2000 (c) 20
  38. 38.Best estimate of 89 × 56? (a) 54000 (b) 5400 (c) 540
  39. 39.Best estimate of 16 × 71? (a) 1400 (b) 14000 (c) 140
  40. 40.Best estimate of 210 + 644? (a) 1000 (b) 600 (c) 800

Answer key

  1. 4500
  2. 2400
  3. 1300
  4. 700
  5. 1200
  6. 400
  7. 1000
  8. 2500
  9. 800
  10. 1100
  11. 600
  12. 800
  13. 1000
  14. 1500
  15. 2100
  16. 500
  17. 900
  18. 1200
  19. 600
  20. 4800
  21. 1300
  22. 600
  23. 900
  24. 900
  25. 800
  26. 400
  27. 700
  28. 1000
  29. 6000
  30. 9000
  31. 900
  32. 3500
  33. 1200
  34. 3500
  35. 900
  36. 2400
  37. 200
  38. 5400
  39. 1400
  40. 800

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