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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 10 · 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 33 × 16? (a) 60 (b) 6000 (c) 600
  2. 2.Best estimate of 68 × 36? (a) 280 (b) 2800 (c) 28000
  3. 3.Best estimate of 162 + 191? (a) 400 (b) 600 (c) 200
  4. 4.Best estimate of 89 × 58? (a) 54000 (b) 5400 (c) 540
  5. 5.Best estimate of 86 × 81? (a) 7200 (b) 720 (c) 72000
  6. 6.Best estimate of 134 + 801? (a) 700 (b) 1100 (c) 900
  7. 7.Best estimate of 57 × 86? (a) 5400 (b) 540 (c) 54000
  8. 8.Best estimate of 80 × 37? (a) 320 (b) 3200 (c) 32000
  9. 9.Best estimate of 728 + 706? (a) 1600 (b) 1200 (c) 1400
  10. 10.Best estimate of 313 + 494? (a) 800 (b) 600 (c) 1000
  11. 11.Best estimate of 229 + 201? (a) 200 (b) 400 (c) 600
  12. 12.Best estimate of 429 + 525? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 30 × 21? (a) 60 (b) 6000 (c) 600
  14. 14.Best estimate of 54 × 67? (a) 350 (b) 35000 (c) 3500
  15. 15.Best estimate of 174 + 854? (a) 900 (b) 1100 (c) 1300
  16. 16.Best estimate of 56 × 29? (a) 1800 (b) 180 (c) 18000
  17. 17.Best estimate of 457 + 206? (a) 700 (b) 900 (c) 500
  18. 18.Best estimate of 767 + 878? (a) 1900 (b) 1500 (c) 1700
  19. 19.Best estimate of 14 × 67? (a) 700 (b) 7000 (c) 70
  20. 20.Best estimate of 16 × 93? (a) 180 (b) 18000 (c) 1800
  21. 21.Best estimate of 471 + 604? (a) 1300 (b) 1100 (c) 900
  22. 22.Best estimate of 31 × 68? (a) 210 (b) 21000 (c) 2100
  23. 23.Best estimate of 43 × 51? (a) 2000 (b) 20000 (c) 200
  24. 24.Best estimate of 43 × 94? (a) 3600 (b) 360 (c) 36000
  25. 25.Best estimate of 48 × 88? (a) 45000 (b) 450 (c) 4500
  26. 26.Best estimate of 38 × 53? (a) 20000 (b) 200 (c) 2000
  27. 27.Best estimate of 82 × 63? (a) 480 (b) 48000 (c) 4800
  28. 28.Best estimate of 88 × 23? (a) 1800 (b) 18000 (c) 180
  29. 29.Best estimate of 46 × 91? (a) 4500 (b) 450 (c) 45000
  30. 30.Best estimate of 763 + 255? (a) 900 (b) 1300 (c) 1100
  31. 31.Best estimate of 310 + 798? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 54 × 40? (a) 20000 (b) 2000 (c) 200
  33. 33.Best estimate of 36 × 30? (a) 120 (b) 12000 (c) 1200
  34. 34.Best estimate of 489 + 415? (a) 900 (b) 700 (c) 1100
  35. 35.Best estimate of 624 + 124? (a) 700 (b) 900 (c) 500
  36. 36.Best estimate of 875 + 276? (a) 1200 (b) 1000 (c) 1400
  37. 37.Best estimate of 59 × 56? (a) 360 (b) 36000 (c) 3600
  38. 38.Best estimate of 72 × 56? (a) 4200 (b) 420 (c) 42000
  39. 39.Best estimate of 16 × 57? (a) 120 (b) 12000 (c) 1200
  40. 40.Best estimate of 18 × 56? (a) 12000 (b) 1200 (c) 120

Answer key

  1. 600
  2. 2800
  3. 400
  4. 5400
  5. 7200
  6. 900
  7. 5400
  8. 3200
  9. 1400
  10. 800
  11. 400
  12. 900
  13. 600
  14. 3500
  15. 1100
  16. 1800
  17. 700
  18. 1700
  19. 700
  20. 1800
  21. 1100
  22. 2100
  23. 2000
  24. 3600
  25. 4500
  26. 2000
  27. 4800
  28. 1800
  29. 4500
  30. 1100
  31. 1100
  32. 2000
  33. 1200
  34. 900
  35. 700
  36. 1200
  37. 3600
  38. 4200
  39. 1200
  40. 1200

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