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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 64 · 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 38 × 41? (a) 16000 (b) 160 (c) 1600
  2. 2.Best estimate of 41 × 52? (a) 2000 (b) 200 (c) 20000
  3. 3.Best estimate of 56 × 98? (a) 600 (b) 60000 (c) 6000
  4. 4.Best estimate of 87 × 79? (a) 7200 (b) 72000 (c) 720
  5. 5.Best estimate of 210 + 238? (a) 600 (b) 400 (c) 200
  6. 6.Best estimate of 22 × 72? (a) 1400 (b) 14000 (c) 140
  7. 7.Best estimate of 21 × 64? (a) 12000 (b) 1200 (c) 120
  8. 8.Best estimate of 47 × 26? (a) 150 (b) 1500 (c) 15000
  9. 9.Best estimate of 837 + 672? (a) 1700 (b) 1300 (c) 1500
  10. 10.Best estimate of 255 + 599? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 29 × 70? (a) 2100 (b) 21000 (c) 210
  12. 12.Best estimate of 51 × 98? (a) 50000 (b) 5000 (c) 500
  13. 13.Best estimate of 235 + 547? (a) 500 (b) 900 (c) 700
  14. 14.Best estimate of 62 × 93? (a) 54000 (b) 540 (c) 5400
  15. 15.Best estimate of 90 × 29? (a) 270 (b) 27000 (c) 2700
  16. 16.Best estimate of 74 × 56? (a) 420 (b) 4200 (c) 42000
  17. 17.Best estimate of 26 × 96? (a) 3000 (b) 300 (c) 30000
  18. 18.Best estimate of 52 × 82? (a) 4000 (b) 40000 (c) 400
  19. 19.Best estimate of 312 + 339? (a) 600 (b) 800 (c) 400
  20. 20.Best estimate of 67 × 34? (a) 21000 (b) 2100 (c) 210
  21. 21.Best estimate of 70 × 12? (a) 7000 (b) 70 (c) 700
  22. 22.Best estimate of 19 × 89? (a) 18000 (b) 180 (c) 1800
  23. 23.Best estimate of 54 × 62? (a) 3000 (b) 300 (c) 30000
  24. 24.Best estimate of 487 + 146? (a) 800 (b) 400 (c) 600
  25. 25.Best estimate of 31 × 73? (a) 2100 (b) 210 (c) 21000
  26. 26.Best estimate of 300 + 240? (a) 300 (b) 500 (c) 700
  27. 27.Best estimate of 12 × 29? (a) 3000 (b) 300 (c) 30
  28. 28.Best estimate of 67 × 16? (a) 140 (b) 14000 (c) 1400
  29. 29.Best estimate of 327 + 151? (a) 300 (b) 700 (c) 500
  30. 30.Best estimate of 87 × 23? (a) 18000 (b) 1800 (c) 180
  31. 31.Best estimate of 145 + 148? (a) 400 (b) 0 (c) 200
  32. 32.Best estimate of 59 × 14? (a) 600 (b) 60 (c) 6000
  33. 33.Best estimate of 26 × 16? (a) 6000 (b) 60 (c) 600
  34. 34.Best estimate of 81 × 22? (a) 1600 (b) 16000 (c) 160
  35. 35.Best estimate of 783 + 203? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 28 × 92? (a) 27000 (b) 270 (c) 2700
  37. 37.Best estimate of 227 + 751? (a) 1200 (b) 800 (c) 1000
  38. 38.Best estimate of 593 + 123? (a) 500 (b) 700 (c) 900
  39. 39.Best estimate of 707 + 763? (a) 1700 (b) 1300 (c) 1500
  40. 40.Best estimate of 29 × 44? (a) 12000 (b) 1200 (c) 120

Answer key

  1. 1600
  2. 2000
  3. 6000
  4. 7200
  5. 400
  6. 1400
  7. 1200
  8. 1500
  9. 1500
  10. 900
  11. 2100
  12. 5000
  13. 700
  14. 5400
  15. 2700
  16. 4200
  17. 3000
  18. 4000
  19. 600
  20. 2100
  21. 700
  22. 1800
  23. 3000
  24. 600
  25. 2100
  26. 500
  27. 300
  28. 1400
  29. 500
  30. 1800
  31. 200
  32. 600
  33. 600
  34. 1600
  35. 1000
  36. 2700
  37. 1000
  38. 700
  39. 1500
  40. 1200

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