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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 545 · 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 39 × 33? (a) 120 (b) 12000 (c) 1200
  2. 2.Best estimate of 128 + 783? (a) 1100 (b) 700 (c) 900
  3. 3.Best estimate of 63 × 54? (a) 300 (b) 3000 (c) 30000
  4. 4.Best estimate of 343 + 151? (a) 700 (b) 500 (c) 300
  5. 5.Best estimate of 24 × 60? (a) 1200 (b) 120 (c) 12000
  6. 6.Best estimate of 26 × 64? (a) 18000 (b) 1800 (c) 180
  7. 7.Best estimate of 855 + 652? (a) 1800 (b) 1400 (c) 1600
  8. 8.Best estimate of 64 × 24? (a) 12000 (b) 120 (c) 1200
  9. 9.Best estimate of 545 + 197? (a) 700 (b) 900 (c) 500
  10. 10.Best estimate of 168 + 302? (a) 300 (b) 700 (c) 500
  11. 11.Best estimate of 89 × 87? (a) 81000 (b) 810 (c) 8100
  12. 12.Best estimate of 66 × 24? (a) 14000 (b) 140 (c) 1400
  13. 13.Best estimate of 527 + 743? (a) 1400 (b) 1200 (c) 1000
  14. 14.Best estimate of 258 + 387? (a) 700 (b) 500 (c) 900
  15. 15.Best estimate of 90 × 51? (a) 450 (b) 45000 (c) 4500
  16. 16.Best estimate of 42 × 70? (a) 28000 (b) 280 (c) 2800
  17. 17.Best estimate of 505 + 503? (a) 1000 (b) 1200 (c) 800
  18. 18.Best estimate of 61 × 79? (a) 4800 (b) 480 (c) 48000
  19. 19.Best estimate of 31 × 24? (a) 60 (b) 600 (c) 6000
  20. 20.Best estimate of 19 × 70? (a) 140 (b) 1400 (c) 14000
  21. 21.Best estimate of 14 × 23? (a) 2000 (b) 200 (c) 20
  22. 22.Best estimate of 70 × 24? (a) 140 (b) 14000 (c) 1400
  23. 23.Best estimate of 57 × 97? (a) 60000 (b) 600 (c) 6000
  24. 24.Best estimate of 876 + 223? (a) 900 (b) 1300 (c) 1100
  25. 25.Best estimate of 37 × 29? (a) 1200 (b) 12000 (c) 120
  26. 26.Best estimate of 167 + 323? (a) 500 (b) 300 (c) 700
  27. 27.Best estimate of 726 + 236? (a) 900 (b) 700 (c) 1100
  28. 28.Best estimate of 21 × 36? (a) 800 (b) 80 (c) 8000
  29. 29.Best estimate of 80 × 32? (a) 24000 (b) 2400 (c) 240
  30. 30.Best estimate of 56 × 52? (a) 3000 (b) 30000 (c) 300
  31. 31.Best estimate of 20 × 16? (a) 40 (b) 4000 (c) 400
  32. 32.Best estimate of 840 + 142? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 98 × 96? (a) 10000 (b) 1000 (c) 100000
  34. 34.Best estimate of 377 + 597? (a) 1200 (b) 1000 (c) 800
  35. 35.Best estimate of 491 + 566? (a) 1100 (b) 900 (c) 1300
  36. 36.Best estimate of 19 × 23? (a) 4000 (b) 400 (c) 40
  37. 37.Best estimate of 406 + 252? (a) 700 (b) 900 (c) 500
  38. 38.Best estimate of 33 × 33? (a) 900 (b) 90 (c) 9000
  39. 39.Best estimate of 279 + 167? (a) 500 (b) 700 (c) 300
  40. 40.Best estimate of 133 + 822? (a) 1100 (b) 900 (c) 700

Answer key

  1. 1200
  2. 900
  3. 3000
  4. 500
  5. 1200
  6. 1800
  7. 1600
  8. 1200
  9. 700
  10. 500
  11. 8100
  12. 1400
  13. 1200
  14. 700
  15. 4500
  16. 2800
  17. 1000
  18. 4800
  19. 600
  20. 1400
  21. 200
  22. 1400
  23. 6000
  24. 1100
  25. 1200
  26. 500
  27. 900
  28. 800
  29. 2400
  30. 3000
  31. 400
  32. 900
  33. 10000
  34. 1000
  35. 1100
  36. 400
  37. 700
  38. 900
  39. 500
  40. 900

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