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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 296 · 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 63 × 76? (a) 480 (b) 4800 (c) 48000
  2. 2.Best estimate of 277 + 248? (a) 500 (b) 700 (c) 300
  3. 3.Best estimate of 67 × 38? (a) 2800 (b) 280 (c) 28000
  4. 4.Best estimate of 90 × 19? (a) 1800 (b) 18000 (c) 180
  5. 5.Best estimate of 871 + 743? (a) 1400 (b) 1800 (c) 1600
  6. 6.Best estimate of 431 + 528? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 46 × 43? (a) 2000 (b) 20000 (c) 200
  8. 8.Best estimate of 48 × 19? (a) 10000 (b) 100 (c) 1000
  9. 9.Best estimate of 94 × 46? (a) 4500 (b) 45000 (c) 450
  10. 10.Best estimate of 16 × 17? (a) 40 (b) 4000 (c) 400
  11. 11.Best estimate of 66 × 12? (a) 7000 (b) 700 (c) 70
  12. 12.Best estimate of 510 + 141? (a) 800 (b) 600 (c) 400
  13. 13.Best estimate of 697 + 155? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 98 × 48? (a) 500 (b) 50000 (c) 5000
  15. 15.Best estimate of 415 + 678? (a) 1100 (b) 1300 (c) 900
  16. 16.Best estimate of 502 + 302? (a) 1000 (b) 800 (c) 600
  17. 17.Best estimate of 172 + 610? (a) 800 (b) 1000 (c) 600
  18. 18.Best estimate of 580 + 237? (a) 1000 (b) 800 (c) 600
  19. 19.Best estimate of 30 × 31? (a) 900 (b) 90 (c) 9000
  20. 20.Best estimate of 72 × 46? (a) 35000 (b) 3500 (c) 350
  21. 21.Best estimate of 30 × 73? (a) 21000 (b) 210 (c) 2100
  22. 22.Best estimate of 68 × 84? (a) 5600 (b) 560 (c) 56000
  23. 23.Best estimate of 80 × 18? (a) 16000 (b) 1600 (c) 160
  24. 24.Best estimate of 79 × 72? (a) 56000 (b) 560 (c) 5600
  25. 25.Best estimate of 94 × 78? (a) 720 (b) 7200 (c) 72000
  26. 26.Best estimate of 83 × 66? (a) 56000 (b) 560 (c) 5600
  27. 27.Best estimate of 403 + 129? (a) 300 (b) 700 (c) 500
  28. 28.Best estimate of 36 × 64? (a) 240 (b) 2400 (c) 24000
  29. 29.Best estimate of 18 × 49? (a) 1000 (b) 100 (c) 10000
  30. 30.Best estimate of 48 × 49? (a) 25000 (b) 2500 (c) 250
  31. 31.Best estimate of 13 × 22? (a) 200 (b) 20 (c) 2000
  32. 32.Best estimate of 36 × 26? (a) 120 (b) 1200 (c) 12000
  33. 33.Best estimate of 79 × 91? (a) 720 (b) 72000 (c) 7200
  34. 34.Best estimate of 96 × 96? (a) 1000 (b) 100000 (c) 10000
  35. 35.Best estimate of 66 × 59? (a) 420 (b) 42000 (c) 4200
  36. 36.Best estimate of 333 + 818? (a) 900 (b) 1300 (c) 1100
  37. 37.Best estimate of 54 × 23? (a) 1000 (b) 10000 (c) 100
  38. 38.Best estimate of 16 × 21? (a) 4000 (b) 40 (c) 400
  39. 39.Best estimate of 66 × 57? (a) 420 (b) 42000 (c) 4200
  40. 40.Best estimate of 80 × 70? (a) 5600 (b) 56000 (c) 560

Answer key

  1. 4800
  2. 500
  3. 2800
  4. 1800
  5. 1600
  6. 900
  7. 2000
  8. 1000
  9. 4500
  10. 400
  11. 700
  12. 600
  13. 900
  14. 5000
  15. 1100
  16. 800
  17. 800
  18. 800
  19. 900
  20. 3500
  21. 2100
  22. 5600
  23. 1600
  24. 5600
  25. 7200
  26. 5600
  27. 500
  28. 2400
  29. 1000
  30. 2500
  31. 200
  32. 1200
  33. 7200
  34. 10000
  35. 4200
  36. 1100
  37. 1000
  38. 400
  39. 4200
  40. 5600

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