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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 189 · 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 × 54? (a) 1000 (b) 100 (c) 10000
  2. 2.Best estimate of 777 + 727? (a) 1500 (b) 1300 (c) 1700
  3. 3.Best estimate of 98 × 17? (a) 20000 (b) 2000 (c) 200
  4. 4.Best estimate of 571 + 400? (a) 1200 (b) 1000 (c) 800
  5. 5.Best estimate of 333 + 199? (a) 300 (b) 500 (c) 700
  6. 6.Best estimate of 44 × 80? (a) 32000 (b) 3200 (c) 320
  7. 7.Best estimate of 73 × 53? (a) 35000 (b) 350 (c) 3500
  8. 8.Best estimate of 20 × 21? (a) 40 (b) 4000 (c) 400
  9. 9.Best estimate of 70 × 62? (a) 4200 (b) 42000 (c) 420
  10. 10.Best estimate of 78 × 18? (a) 16000 (b) 1600 (c) 160
  11. 11.Best estimate of 177 + 512? (a) 900 (b) 700 (c) 500
  12. 12.Best estimate of 476 + 526? (a) 800 (b) 1200 (c) 1000
  13. 13.Best estimate of 34 × 56? (a) 18000 (b) 180 (c) 1800
  14. 14.Best estimate of 46 × 69? (a) 350 (b) 3500 (c) 35000
  15. 15.Best estimate of 873 + 264? (a) 1200 (b) 1000 (c) 1400
  16. 16.Best estimate of 156 + 515? (a) 700 (b) 900 (c) 500
  17. 17.Best estimate of 73 × 96? (a) 70000 (b) 700 (c) 7000
  18. 18.Best estimate of 283 + 658? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 154 + 154? (a) 200 (b) 400 (c) 600
  20. 20.Best estimate of 32 × 37? (a) 1200 (b) 12000 (c) 120
  21. 21.Best estimate of 806 + 470? (a) 1300 (b) 1100 (c) 1500
  22. 22.Best estimate of 223 + 347? (a) 500 (b) 700 (c) 300
  23. 23.Best estimate of 76 × 13? (a) 8000 (b) 80 (c) 800
  24. 24.Best estimate of 31 × 86? (a) 270 (b) 2700 (c) 27000
  25. 25.Best estimate of 60 × 81? (a) 48000 (b) 480 (c) 4800
  26. 26.Best estimate of 26 × 17? (a) 6000 (b) 60 (c) 600
  27. 27.Best estimate of 54 × 47? (a) 2500 (b) 25000 (c) 250
  28. 28.Best estimate of 33 × 26? (a) 900 (b) 90 (c) 9000
  29. 29.Best estimate of 83 × 89? (a) 72000 (b) 720 (c) 7200
  30. 30.Best estimate of 62 × 12? (a) 600 (b) 60 (c) 6000
  31. 31.Best estimate of 143 + 295? (a) 600 (b) 200 (c) 400
  32. 32.Best estimate of 348 + 742? (a) 1000 (b) 1200 (c) 800
  33. 33.Best estimate of 500 + 294? (a) 800 (b) 600 (c) 1000
  34. 34.Best estimate of 639 + 540? (a) 900 (b) 1300 (c) 1100
  35. 35.Best estimate of 91 × 93? (a) 8100 (b) 81000 (c) 810
  36. 36.Best estimate of 24 × 84? (a) 160 (b) 16000 (c) 1600
  37. 37.Best estimate of 667 + 284? (a) 1000 (b) 800 (c) 1200
  38. 38.Best estimate of 97 × 27? (a) 30000 (b) 3000 (c) 300
  39. 39.Best estimate of 16 × 12? (a) 2000 (b) 200 (c) 20
  40. 40.Best estimate of 16 × 76? (a) 1600 (b) 16000 (c) 160

Answer key

  1. 1000
  2. 1500
  3. 2000
  4. 1000
  5. 500
  6. 3200
  7. 3500
  8. 400
  9. 4200
  10. 1600
  11. 700
  12. 1000
  13. 1800
  14. 3500
  15. 1200
  16. 700
  17. 7000
  18. 1000
  19. 400
  20. 1200
  21. 1300
  22. 500
  23. 800
  24. 2700
  25. 4800
  26. 600
  27. 2500
  28. 900
  29. 7200
  30. 600
  31. 400
  32. 1000
  33. 800
  34. 1100
  35. 8100
  36. 1600
  37. 1000
  38. 3000
  39. 200
  40. 1600

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