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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 254 · 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 70 × 62? (a) 42000 (b) 420 (c) 4200
  2. 2.Best estimate of 42 × 32? (a) 12000 (b) 1200 (c) 120
  3. 3.Best estimate of 542 + 562? (a) 900 (b) 1100 (c) 1300
  4. 4.Best estimate of 96 × 46? (a) 50000 (b) 5000 (c) 500
  5. 5.Best estimate of 12 × 80? (a) 80 (b) 8000 (c) 800
  6. 6.Best estimate of 87 × 49? (a) 4500 (b) 45000 (c) 450
  7. 7.Best estimate of 159 + 563? (a) 800 (b) 1000 (c) 600
  8. 8.Best estimate of 98 × 28? (a) 3000 (b) 30000 (c) 300
  9. 9.Best estimate of 47 × 76? (a) 4000 (b) 400 (c) 40000
  10. 10.Best estimate of 91 × 53? (a) 45000 (b) 4500 (c) 450
  11. 11.Best estimate of 49 × 36? (a) 2000 (b) 20000 (c) 200
  12. 12.Best estimate of 254 + 396? (a) 900 (b) 500 (c) 700
  13. 13.Best estimate of 96 × 51? (a) 5000 (b) 50000 (c) 500
  14. 14.Best estimate of 28 × 83? (a) 240 (b) 24000 (c) 2400
  15. 15.Best estimate of 712 + 509? (a) 1000 (b) 1200 (c) 1400
  16. 16.Best estimate of 96 × 78? (a) 80000 (b) 800 (c) 8000
  17. 17.Best estimate of 96 × 16? (a) 2000 (b) 200 (c) 20000
  18. 18.Best estimate of 17 × 51? (a) 1000 (b) 100 (c) 10000
  19. 19.Best estimate of 26 × 70? (a) 210 (b) 21000 (c) 2100
  20. 20.Best estimate of 792 + 633? (a) 1600 (b) 1400 (c) 1200
  21. 21.Best estimate of 91 × 92? (a) 8100 (b) 81000 (c) 810
  22. 22.Best estimate of 79 × 21? (a) 16000 (b) 1600 (c) 160
  23. 23.Best estimate of 12 × 66? (a) 7000 (b) 70 (c) 700
  24. 24.Best estimate of 16 × 48? (a) 1000 (b) 100 (c) 10000
  25. 25.Best estimate of 62 × 93? (a) 5400 (b) 54000 (c) 540
  26. 26.Best estimate of 62 × 28? (a) 180 (b) 1800 (c) 18000
  27. 27.Best estimate of 30 × 56? (a) 1800 (b) 18000 (c) 180
  28. 28.Best estimate of 46 × 56? (a) 30000 (b) 3000 (c) 300
  29. 29.Best estimate of 84 × 28? (a) 2400 (b) 240 (c) 24000
  30. 30.Best estimate of 44 × 96? (a) 400 (b) 40000 (c) 4000
  31. 31.Best estimate of 56 × 88? (a) 5400 (b) 540 (c) 54000
  32. 32.Best estimate of 609 + 272? (a) 900 (b) 700 (c) 1100
  33. 33.Best estimate of 179 + 629? (a) 800 (b) 600 (c) 1000
  34. 34.Best estimate of 72 × 16? (a) 140 (b) 14000 (c) 1400
  35. 35.Best estimate of 40 × 76? (a) 320 (b) 32000 (c) 3200
  36. 36.Best estimate of 40 × 60? (a) 24000 (b) 2400 (c) 240
  37. 37.Best estimate of 31 × 64? (a) 18000 (b) 1800 (c) 180
  38. 38.Best estimate of 735 + 329? (a) 800 (b) 1000 (c) 1200
  39. 39.Best estimate of 12 × 19? (a) 2000 (b) 200 (c) 20
  40. 40.Best estimate of 63 × 89? (a) 5400 (b) 540 (c) 54000

Answer key

  1. 4200
  2. 1200
  3. 1100
  4. 5000
  5. 800
  6. 4500
  7. 800
  8. 3000
  9. 4000
  10. 4500
  11. 2000
  12. 700
  13. 5000
  14. 2400
  15. 1200
  16. 8000
  17. 2000
  18. 1000
  19. 2100
  20. 1400
  21. 8100
  22. 1600
  23. 700
  24. 1000
  25. 5400
  26. 1800
  27. 1800
  28. 3000
  29. 2400
  30. 4000
  31. 5400
  32. 900
  33. 800
  34. 1400
  35. 3200
  36. 2400
  37. 1800
  38. 1000
  39. 200
  40. 5400

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