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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 936 · 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 84 × 49? (a) 400 (b) 40000 (c) 4000
  2. 2.Best estimate of 34 × 86? (a) 27000 (b) 2700 (c) 270
  3. 3.Best estimate of 851 + 462? (a) 1600 (b) 1400 (c) 1200
  4. 4.Best estimate of 47 × 38? (a) 200 (b) 2000 (c) 20000
  5. 5.Best estimate of 486 + 463? (a) 1000 (b) 800 (c) 1200
  6. 6.Best estimate of 83 × 26? (a) 24000 (b) 240 (c) 2400
  7. 7.Best estimate of 824 + 651? (a) 1500 (b) 1300 (c) 1700
  8. 8.Best estimate of 14 × 36? (a) 40 (b) 400 (c) 4000
  9. 9.Best estimate of 26 × 37? (a) 12000 (b) 120 (c) 1200
  10. 10.Best estimate of 142 + 493? (a) 800 (b) 400 (c) 600
  11. 11.Best estimate of 21 × 70? (a) 14000 (b) 140 (c) 1400
  12. 12.Best estimate of 482 + 469? (a) 1200 (b) 800 (c) 1000
  13. 13.Best estimate of 352 + 574? (a) 1200 (b) 1000 (c) 800
  14. 14.Best estimate of 33 × 79? (a) 2400 (b) 24000 (c) 240
  15. 15.Best estimate of 797 + 475? (a) 1300 (b) 1100 (c) 1500
  16. 16.Best estimate of 48 × 19? (a) 100 (b) 1000 (c) 10000
  17. 17.Best estimate of 630 + 336? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 199 + 511? (a) 500 (b) 700 (c) 900
  19. 19.Best estimate of 138 + 713? (a) 600 (b) 1000 (c) 800
  20. 20.Best estimate of 613 + 282? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 37 × 33? (a) 1200 (b) 12000 (c) 120
  22. 22.Best estimate of 302 + 576? (a) 700 (b) 1100 (c) 900
  23. 23.Best estimate of 800 + 393? (a) 1200 (b) 1000 (c) 1400
  24. 24.Best estimate of 265 + 653? (a) 800 (b) 1000 (c) 1200
  25. 25.Best estimate of 63 × 88? (a) 540 (b) 54000 (c) 5400
  26. 26.Best estimate of 748 + 218? (a) 700 (b) 1100 (c) 900
  27. 27.Best estimate of 93 × 63? (a) 54000 (b) 540 (c) 5400
  28. 28.Best estimate of 32 × 67? (a) 21000 (b) 210 (c) 2100
  29. 29.Best estimate of 88 × 47? (a) 45000 (b) 450 (c) 4500
  30. 30.Best estimate of 82 × 79? (a) 6400 (b) 640 (c) 64000
  31. 31.Best estimate of 27 × 57? (a) 18000 (b) 180 (c) 1800
  32. 32.Best estimate of 558 + 536? (a) 1100 (b) 900 (c) 1300
  33. 33.Best estimate of 430 + 362? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 376 + 715? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 13 × 79? (a) 800 (b) 80 (c) 8000
  36. 36.Best estimate of 42 × 83? (a) 320 (b) 3200 (c) 32000
  37. 37.Best estimate of 401 + 349? (a) 500 (b) 900 (c) 700
  38. 38.Best estimate of 76 × 52? (a) 40000 (b) 400 (c) 4000
  39. 39.Best estimate of 816 + 151? (a) 1200 (b) 800 (c) 1000
  40. 40.Best estimate of 437 + 335? (a) 900 (b) 700 (c) 500

Answer key

  1. 4000
  2. 2700
  3. 1400
  4. 2000
  5. 1000
  6. 2400
  7. 1500
  8. 400
  9. 1200
  10. 600
  11. 1400
  12. 1000
  13. 1000
  14. 2400
  15. 1300
  16. 1000
  17. 900
  18. 700
  19. 800
  20. 900
  21. 1200
  22. 900
  23. 1200
  24. 1000
  25. 5400
  26. 900
  27. 5400
  28. 2100
  29. 4500
  30. 6400
  31. 1800
  32. 1100
  33. 800
  34. 1100
  35. 800
  36. 3200
  37. 700
  38. 4000
  39. 1000
  40. 700

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