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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 381 · 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 94 × 96? (a) 9000 (b) 900 (c) 90000
  2. 2.Best estimate of 90 × 96? (a) 9000 (b) 90000 (c) 900
  3. 3.Best estimate of 161 + 749? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 78 × 42? (a) 32000 (b) 3200 (c) 320
  5. 5.Best estimate of 259 + 293? (a) 800 (b) 600 (c) 400
  6. 6.Best estimate of 529 + 472? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 136 + 644? (a) 700 (b) 500 (c) 900
  8. 8.Best estimate of 29 × 94? (a) 270 (b) 27000 (c) 2700
  9. 9.Best estimate of 481 + 201? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 810 + 703? (a) 1300 (b) 1500 (c) 1700
  11. 11.Best estimate of 66 × 73? (a) 490 (b) 49000 (c) 4900
  12. 12.Best estimate of 519 + 255? (a) 1000 (b) 600 (c) 800
  13. 13.Best estimate of 825 + 802? (a) 1600 (b) 1800 (c) 1400
  14. 14.Best estimate of 212 + 487? (a) 900 (b) 700 (c) 500
  15. 15.Best estimate of 779 + 449? (a) 1000 (b) 1400 (c) 1200
  16. 16.Best estimate of 480 + 671? (a) 1000 (b) 1200 (c) 1400
  17. 17.Best estimate of 527 + 178? (a) 900 (b) 500 (c) 700
  18. 18.Best estimate of 42 × 40? (a) 1600 (b) 160 (c) 16000
  19. 19.Best estimate of 771 + 254? (a) 1300 (b) 900 (c) 1100
  20. 20.Best estimate of 66 × 13? (a) 70 (b) 7000 (c) 700
  21. 21.Best estimate of 559 + 518? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 84 × 47? (a) 4000 (b) 40000 (c) 400
  23. 23.Best estimate of 51 × 30? (a) 15000 (b) 150 (c) 1500
  24. 24.Best estimate of 397 + 225? (a) 600 (b) 800 (c) 400
  25. 25.Best estimate of 446 + 506? (a) 900 (b) 1100 (c) 700
  26. 26.Best estimate of 589 + 790? (a) 1400 (b) 1600 (c) 1200
  27. 27.Best estimate of 288 + 844? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 321 + 406? (a) 700 (b) 500 (c) 900
  29. 29.Best estimate of 63 × 87? (a) 5400 (b) 540 (c) 54000
  30. 30.Best estimate of 427 + 755? (a) 1400 (b) 1000 (c) 1200
  31. 31.Best estimate of 330 + 725? (a) 800 (b) 1000 (c) 1200
  32. 32.Best estimate of 44 × 53? (a) 200 (b) 2000 (c) 20000
  33. 33.Best estimate of 603 + 707? (a) 1300 (b) 1100 (c) 1500
  34. 34.Best estimate of 19 × 36? (a) 800 (b) 8000 (c) 80
  35. 35.Best estimate of 331 + 665? (a) 1200 (b) 1000 (c) 800
  36. 36.Best estimate of 52 × 67? (a) 3500 (b) 35000 (c) 350
  37. 37.Best estimate of 77 × 27? (a) 2400 (b) 240 (c) 24000
  38. 38.Best estimate of 583 + 445? (a) 1200 (b) 1000 (c) 800
  39. 39.Best estimate of 28 × 81? (a) 240 (b) 24000 (c) 2400
  40. 40.Best estimate of 145 + 272? (a) 200 (b) 400 (c) 600

Answer key

  1. 9000
  2. 9000
  3. 900
  4. 3200
  5. 600
  6. 1000
  7. 700
  8. 2700
  9. 700
  10. 1500
  11. 4900
  12. 800
  13. 1600
  14. 700
  15. 1200
  16. 1200
  17. 700
  18. 1600
  19. 1100
  20. 700
  21. 1100
  22. 4000
  23. 1500
  24. 600
  25. 900
  26. 1400
  27. 1100
  28. 700
  29. 5400
  30. 1200
  31. 1000
  32. 2000
  33. 1300
  34. 800
  35. 1000
  36. 3500
  37. 2400
  38. 1000
  39. 2400
  40. 400

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