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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 276 · 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 867 + 879? (a) 2000 (b) 1600 (c) 1800
  2. 2.Best estimate of 17 × 84? (a) 16000 (b) 160 (c) 1600
  3. 3.Best estimate of 64 × 38? (a) 24000 (b) 2400 (c) 240
  4. 4.Best estimate of 12 × 48? (a) 5000 (b) 500 (c) 50
  5. 5.Best estimate of 76 × 19? (a) 1600 (b) 160 (c) 16000
  6. 6.Best estimate of 776 + 255? (a) 1300 (b) 900 (c) 1100
  7. 7.Best estimate of 766 + 295? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 69 × 21? (a) 14000 (b) 140 (c) 1400
  9. 9.Best estimate of 526 + 552? (a) 900 (b) 1300 (c) 1100
  10. 10.Best estimate of 417 + 707? (a) 1300 (b) 1100 (c) 900
  11. 11.Best estimate of 69 × 62? (a) 420 (b) 42000 (c) 4200
  12. 12.Best estimate of 857 + 645? (a) 1500 (b) 1300 (c) 1700
  13. 13.Best estimate of 344 + 676? (a) 800 (b) 1200 (c) 1000
  14. 14.Best estimate of 17 × 43? (a) 8000 (b) 80 (c) 800
  15. 15.Best estimate of 38 × 79? (a) 3200 (b) 320 (c) 32000
  16. 16.Best estimate of 26 × 86? (a) 2700 (b) 270 (c) 27000
  17. 17.Best estimate of 74 × 42? (a) 280 (b) 28000 (c) 2800
  18. 18.Best estimate of 62 × 24? (a) 12000 (b) 120 (c) 1200
  19. 19.Best estimate of 23 × 17? (a) 40 (b) 400 (c) 4000
  20. 20.Best estimate of 189 + 411? (a) 800 (b) 400 (c) 600
  21. 21.Best estimate of 151 + 243? (a) 200 (b) 400 (c) 600
  22. 22.Best estimate of 57 × 94? (a) 540 (b) 5400 (c) 54000
  23. 23.Best estimate of 323 + 197? (a) 700 (b) 500 (c) 300
  24. 24.Best estimate of 83 × 49? (a) 400 (b) 4000 (c) 40000
  25. 25.Best estimate of 67 × 66? (a) 49000 (b) 4900 (c) 490
  26. 26.Best estimate of 96 × 36? (a) 4000 (b) 40000 (c) 400
  27. 27.Best estimate of 19 × 51? (a) 10000 (b) 1000 (c) 100
  28. 28.Best estimate of 21 × 50? (a) 100 (b) 1000 (c) 10000
  29. 29.Best estimate of 345 + 377? (a) 900 (b) 500 (c) 700
  30. 30.Best estimate of 94 × 23? (a) 1800 (b) 18000 (c) 180
  31. 31.Best estimate of 400 + 522? (a) 700 (b) 900 (c) 1100
  32. 32.Best estimate of 48 × 54? (a) 250 (b) 2500 (c) 25000
  33. 33.Best estimate of 556 + 333? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 877 + 159? (a) 900 (b) 1300 (c) 1100
  35. 35.Best estimate of 12 × 52? (a) 500 (b) 50 (c) 5000
  36. 36.Best estimate of 18 × 74? (a) 1400 (b) 140 (c) 14000
  37. 37.Best estimate of 418 + 259? (a) 500 (b) 900 (c) 700
  38. 38.Best estimate of 42 × 37? (a) 1600 (b) 16000 (c) 160
  39. 39.Best estimate of 76 × 40? (a) 32000 (b) 320 (c) 3200
  40. 40.Best estimate of 38 × 62? (a) 240 (b) 24000 (c) 2400

Answer key

  1. 1800
  2. 1600
  3. 2400
  4. 500
  5. 1600
  6. 1100
  7. 1100
  8. 1400
  9. 1100
  10. 1100
  11. 4200
  12. 1500
  13. 1000
  14. 800
  15. 3200
  16. 2700
  17. 2800
  18. 1200
  19. 400
  20. 600
  21. 400
  22. 5400
  23. 500
  24. 4000
  25. 4900
  26. 4000
  27. 1000
  28. 1000
  29. 700
  30. 1800
  31. 900
  32. 2500
  33. 900
  34. 1100
  35. 500
  36. 1400
  37. 700
  38. 1600
  39. 3200
  40. 2400

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