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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 709 · 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 57 × 68? (a) 42000 (b) 420 (c) 4200
  2. 2.Best estimate of 856 + 557? (a) 1300 (b) 1500 (c) 1700
  3. 3.Best estimate of 92 × 13? (a) 90 (b) 9000 (c) 900
  4. 4.Best estimate of 493 + 336? (a) 800 (b) 1000 (c) 600
  5. 5.Best estimate of 81 × 32? (a) 240 (b) 24000 (c) 2400
  6. 6.Best estimate of 19 × 49? (a) 1000 (b) 10000 (c) 100
  7. 7.Best estimate of 31 × 17? (a) 6000 (b) 60 (c) 600
  8. 8.Best estimate of 218 + 228? (a) 400 (b) 200 (c) 600
  9. 9.Best estimate of 86 × 81? (a) 7200 (b) 720 (c) 72000
  10. 10.Best estimate of 697 + 618? (a) 1100 (b) 1500 (c) 1300
  11. 11.Best estimate of 90 × 16? (a) 18000 (b) 180 (c) 1800
  12. 12.Best estimate of 197 + 533? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 33 × 90? (a) 2700 (b) 270 (c) 27000
  14. 14.Best estimate of 46 × 64? (a) 300 (b) 3000 (c) 30000
  15. 15.Best estimate of 24 × 98? (a) 200 (b) 2000 (c) 20000
  16. 16.Best estimate of 866 + 376? (a) 1100 (b) 1500 (c) 1300
  17. 17.Best estimate of 23 × 26? (a) 6000 (b) 600 (c) 60
  18. 18.Best estimate of 234 + 840? (a) 800 (b) 1000 (c) 1200
  19. 19.Best estimate of 184 + 123? (a) 500 (b) 300 (c) 100
  20. 20.Best estimate of 37 × 94? (a) 3600 (b) 36000 (c) 360
  21. 21.Best estimate of 843 + 181? (a) 1200 (b) 1000 (c) 800
  22. 22.Best estimate of 18 × 53? (a) 100 (b) 10000 (c) 1000
  23. 23.Best estimate of 88 × 23? (a) 18000 (b) 1800 (c) 180
  24. 24.Best estimate of 84 × 43? (a) 3200 (b) 32000 (c) 320
  25. 25.Best estimate of 56 × 41? (a) 240 (b) 24000 (c) 2400
  26. 26.Best estimate of 74 × 20? (a) 1400 (b) 14000 (c) 140
  27. 27.Best estimate of 20 × 36? (a) 80 (b) 800 (c) 8000
  28. 28.Best estimate of 160 + 811? (a) 1200 (b) 800 (c) 1000
  29. 29.Best estimate of 154 + 137? (a) 300 (b) 100 (c) 500
  30. 30.Best estimate of 81 × 31? (a) 240 (b) 2400 (c) 24000
  31. 31.Best estimate of 96 × 31? (a) 30000 (b) 300 (c) 3000
  32. 32.Best estimate of 530 + 240? (a) 700 (b) 900 (c) 500
  33. 33.Best estimate of 266 + 392? (a) 500 (b) 700 (c) 900
  34. 34.Best estimate of 204 + 541? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 70 × 16? (a) 1400 (b) 140 (c) 14000
  36. 36.Best estimate of 62 × 34? (a) 1800 (b) 180 (c) 18000
  37. 37.Best estimate of 30 × 14? (a) 3000 (b) 300 (c) 30
  38. 38.Best estimate of 417 + 598? (a) 1200 (b) 1000 (c) 800
  39. 39.Best estimate of 29 × 42? (a) 120 (b) 12000 (c) 1200
  40. 40.Best estimate of 33 × 37? (a) 1200 (b) 120 (c) 12000

Answer key

  1. 4200
  2. 1500
  3. 900
  4. 800
  5. 2400
  6. 1000
  7. 600
  8. 400
  9. 7200
  10. 1300
  11. 1800
  12. 700
  13. 2700
  14. 3000
  15. 2000
  16. 1300
  17. 600
  18. 1000
  19. 300
  20. 3600
  21. 1000
  22. 1000
  23. 1800
  24. 3200
  25. 2400
  26. 1400
  27. 800
  28. 1000
  29. 300
  30. 2400
  31. 3000
  32. 700
  33. 700
  34. 700
  35. 1400
  36. 1800
  37. 300
  38. 1000
  39. 1200
  40. 1200

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