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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 939 · 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 21 × 87? (a) 180 (b) 18000 (c) 1800
  2. 2.Best estimate of 16 × 16? (a) 4000 (b) 40 (c) 400
  3. 3.Best estimate of 682 + 766? (a) 1500 (b) 1700 (c) 1300
  4. 4.Best estimate of 343 + 239? (a) 500 (b) 700 (c) 300
  5. 5.Best estimate of 89 × 14? (a) 90 (b) 900 (c) 9000
  6. 6.Best estimate of 54 × 21? (a) 10000 (b) 1000 (c) 100
  7. 7.Best estimate of 834 + 228? (a) 1000 (b) 1200 (c) 800
  8. 8.Best estimate of 733 + 534? (a) 1000 (b) 1200 (c) 1400
  9. 9.Best estimate of 423 + 569? (a) 800 (b) 1000 (c) 1200
  10. 10.Best estimate of 86 × 54? (a) 4500 (b) 45000 (c) 450
  11. 11.Best estimate of 63 × 96? (a) 6000 (b) 60000 (c) 600
  12. 12.Best estimate of 509 + 383? (a) 700 (b) 1100 (c) 900
  13. 13.Best estimate of 28 × 28? (a) 9000 (b) 900 (c) 90
  14. 14.Best estimate of 314 + 526? (a) 1000 (b) 600 (c) 800
  15. 15.Best estimate of 307 + 789? (a) 1100 (b) 900 (c) 1300
  16. 16.Best estimate of 43 × 81? (a) 32000 (b) 320 (c) 3200
  17. 17.Best estimate of 555 + 326? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 326 + 283? (a) 600 (b) 400 (c) 800
  19. 19.Best estimate of 407 + 571? (a) 1200 (b) 1000 (c) 800
  20. 20.Best estimate of 66 × 39? (a) 280 (b) 2800 (c) 28000
  21. 21.Best estimate of 17 × 27? (a) 60 (b) 600 (c) 6000
  22. 22.Best estimate of 58 × 98? (a) 6000 (b) 60000 (c) 600
  23. 23.Best estimate of 220 + 192? (a) 400 (b) 200 (c) 600
  24. 24.Best estimate of 144 + 301? (a) 600 (b) 200 (c) 400
  25. 25.Best estimate of 257 + 167? (a) 500 (b) 300 (c) 700
  26. 26.Best estimate of 77 × 14? (a) 800 (b) 8000 (c) 80
  27. 27.Best estimate of 300 + 266? (a) 400 (b) 800 (c) 600
  28. 28.Best estimate of 61 × 13? (a) 60 (b) 600 (c) 6000
  29. 29.Best estimate of 32 × 43? (a) 1200 (b) 120 (c) 12000
  30. 30.Best estimate of 47 × 89? (a) 450 (b) 4500 (c) 45000
  31. 31.Best estimate of 86 × 86? (a) 810 (b) 8100 (c) 81000
  32. 32.Best estimate of 793 + 809? (a) 1800 (b) 1600 (c) 1400
  33. 33.Best estimate of 43 × 88? (a) 3600 (b) 36000 (c) 360
  34. 34.Best estimate of 628 + 523? (a) 1300 (b) 900 (c) 1100
  35. 35.Best estimate of 399 + 327? (a) 500 (b) 700 (c) 900
  36. 36.Best estimate of 140 + 497? (a) 400 (b) 600 (c) 800
  37. 37.Best estimate of 91 × 96? (a) 900 (b) 9000 (c) 90000
  38. 38.Best estimate of 73 × 20? (a) 140 (b) 14000 (c) 1400
  39. 39.Best estimate of 17 × 44? (a) 80 (b) 800 (c) 8000
  40. 40.Best estimate of 406 + 576? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 1800
  2. 400
  3. 1500
  4. 500
  5. 900
  6. 1000
  7. 1000
  8. 1200
  9. 1000
  10. 4500
  11. 6000
  12. 900
  13. 900
  14. 800
  15. 1100
  16. 3200
  17. 900
  18. 600
  19. 1000
  20. 2800
  21. 600
  22. 6000
  23. 400
  24. 400
  25. 500
  26. 800
  27. 600
  28. 600
  29. 1200
  30. 4500
  31. 8100
  32. 1600
  33. 3600
  34. 1100
  35. 700
  36. 600
  37. 9000
  38. 1400
  39. 800
  40. 1000

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