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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 887 · 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 712 + 793? (a) 1700 (b) 1300 (c) 1500
  2. 2.Best estimate of 826 + 338? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 69 × 39? (a) 2800 (b) 28000 (c) 280
  4. 4.Best estimate of 79 × 76? (a) 64000 (b) 640 (c) 6400
  5. 5.Best estimate of 128 + 409? (a) 700 (b) 500 (c) 300
  6. 6.Best estimate of 854 + 364? (a) 1500 (b) 1300 (c) 1100
  7. 7.Best estimate of 54 × 46? (a) 2500 (b) 25000 (c) 250
  8. 8.Best estimate of 66 × 46? (a) 35000 (b) 3500 (c) 350
  9. 9.Best estimate of 845 + 644? (a) 1200 (b) 1400 (c) 1600
  10. 10.Best estimate of 86 × 76? (a) 72000 (b) 7200 (c) 720
  11. 11.Best estimate of 47 × 73? (a) 35000 (b) 3500 (c) 350
  12. 12.Best estimate of 93 × 51? (a) 45000 (b) 4500 (c) 450
  13. 13.Best estimate of 194 + 875? (a) 900 (b) 1300 (c) 1100
  14. 14.Best estimate of 56 × 56? (a) 360 (b) 3600 (c) 36000
  15. 15.Best estimate of 205 + 151? (a) 200 (b) 600 (c) 400
  16. 16.Best estimate of 53 × 79? (a) 40000 (b) 400 (c) 4000
  17. 17.Best estimate of 56 × 23? (a) 1200 (b) 120 (c) 12000
  18. 18.Best estimate of 54 × 60? (a) 3000 (b) 30000 (c) 300
  19. 19.Best estimate of 139 + 695? (a) 800 (b) 1000 (c) 600
  20. 20.Best estimate of 223 + 804? (a) 1200 (b) 1000 (c) 800
  21. 21.Best estimate of 183 + 158? (a) 400 (b) 600 (c) 200
  22. 22.Best estimate of 83 × 23? (a) 1600 (b) 16000 (c) 160
  23. 23.Best estimate of 363 + 428? (a) 1000 (b) 800 (c) 600
  24. 24.Best estimate of 656 + 542? (a) 1400 (b) 1000 (c) 1200
  25. 25.Best estimate of 13 × 19? (a) 200 (b) 2000 (c) 20
  26. 26.Best estimate of 53 × 16? (a) 10000 (b) 1000 (c) 100
  27. 27.Best estimate of 50 × 93? (a) 45000 (b) 450 (c) 4500
  28. 28.Best estimate of 79 × 68? (a) 5600 (b) 56000 (c) 560
  29. 29.Best estimate of 770 + 168? (a) 800 (b) 1200 (c) 1000
  30. 30.Best estimate of 54 × 66? (a) 35000 (b) 3500 (c) 350
  31. 31.Best estimate of 81 × 49? (a) 400 (b) 40000 (c) 4000
  32. 32.Best estimate of 510 + 369? (a) 700 (b) 900 (c) 1100
  33. 33.Best estimate of 230 + 666? (a) 700 (b) 900 (c) 1100
  34. 34.Best estimate of 91 × 40? (a) 360 (b) 3600 (c) 36000
  35. 35.Best estimate of 448 + 660? (a) 1100 (b) 1300 (c) 900
  36. 36.Best estimate of 31 × 71? (a) 2100 (b) 21000 (c) 210
  37. 37.Best estimate of 52 × 89? (a) 450 (b) 4500 (c) 45000
  38. 38.Best estimate of 803 + 200? (a) 800 (b) 1200 (c) 1000
  39. 39.Best estimate of 43 × 56? (a) 24000 (b) 2400 (c) 240
  40. 40.Best estimate of 151 + 479? (a) 900 (b) 700 (c) 500

Answer key

  1. 1500
  2. 1100
  3. 2800
  4. 6400
  5. 500
  6. 1300
  7. 2500
  8. 3500
  9. 1400
  10. 7200
  11. 3500
  12. 4500
  13. 1100
  14. 3600
  15. 400
  16. 4000
  17. 1200
  18. 3000
  19. 800
  20. 1000
  21. 400
  22. 1600
  23. 800
  24. 1200
  25. 200
  26. 1000
  27. 4500
  28. 5600
  29. 1000
  30. 3500
  31. 4000
  32. 900
  33. 900
  34. 3600
  35. 1100
  36. 2100
  37. 4500
  38. 1000
  39. 2400
  40. 700

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