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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 147 · 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 424 + 330? (a) 500 (b) 700 (c) 900
  2. 2.Best estimate of 26 × 49? (a) 15000 (b) 150 (c) 1500
  3. 3.Best estimate of 96 × 92? (a) 90000 (b) 900 (c) 9000
  4. 4.Best estimate of 40 × 77? (a) 3200 (b) 320 (c) 32000
  5. 5.Best estimate of 483 + 768? (a) 1300 (b) 1100 (c) 1500
  6. 6.Best estimate of 244 + 675? (a) 700 (b) 1100 (c) 900
  7. 7.Best estimate of 399 + 796? (a) 1400 (b) 1200 (c) 1000
  8. 8.Best estimate of 36 × 70? (a) 28000 (b) 280 (c) 2800
  9. 9.Best estimate of 392 + 467? (a) 900 (b) 1100 (c) 700
  10. 10.Best estimate of 163 + 719? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 31 × 20? (a) 6000 (b) 60 (c) 600
  12. 12.Best estimate of 756 + 547? (a) 1500 (b) 1100 (c) 1300
  13. 13.Best estimate of 98 × 96? (a) 1000 (b) 100000 (c) 10000
  14. 14.Best estimate of 48 × 94? (a) 45000 (b) 4500 (c) 450
  15. 15.Best estimate of 63 × 18? (a) 12000 (b) 1200 (c) 120
  16. 16.Best estimate of 21 × 47? (a) 1000 (b) 10000 (c) 100
  17. 17.Best estimate of 26 × 58? (a) 18000 (b) 1800 (c) 180
  18. 18.Best estimate of 337 + 626? (a) 900 (b) 700 (c) 1100
  19. 19.Best estimate of 94 × 89? (a) 81000 (b) 8100 (c) 810
  20. 20.Best estimate of 157 + 400? (a) 400 (b) 800 (c) 600
  21. 21.Best estimate of 235 + 244? (a) 400 (b) 200 (c) 600
  22. 22.Best estimate of 27 × 22? (a) 60 (b) 600 (c) 6000
  23. 23.Best estimate of 53 × 27? (a) 1500 (b) 150 (c) 15000
  24. 24.Best estimate of 71 × 90? (a) 63000 (b) 630 (c) 6300
  25. 25.Best estimate of 52 × 48? (a) 2500 (b) 250 (c) 25000
  26. 26.Best estimate of 656 + 635? (a) 1300 (b) 1100 (c) 1500
  27. 27.Best estimate of 389 + 571? (a) 1000 (b) 800 (c) 1200
  28. 28.Best estimate of 60 × 62? (a) 360 (b) 36000 (c) 3600
  29. 29.Best estimate of 48 × 52? (a) 25000 (b) 250 (c) 2500
  30. 30.Best estimate of 632 + 353? (a) 800 (b) 1200 (c) 1000
  31. 31.Best estimate of 24 × 63? (a) 120 (b) 12000 (c) 1200
  32. 32.Best estimate of 46 × 36? (a) 2000 (b) 20000 (c) 200
  33. 33.Best estimate of 17 × 79? (a) 160 (b) 16000 (c) 1600
  34. 34.Best estimate of 24 × 50? (a) 1000 (b) 10000 (c) 100
  35. 35.Best estimate of 851 + 251? (a) 1400 (b) 1000 (c) 1200
  36. 36.Best estimate of 70 × 86? (a) 630 (b) 63000 (c) 6300
  37. 37.Best estimate of 21 × 91? (a) 18000 (b) 180 (c) 1800
  38. 38.Best estimate of 49 × 77? (a) 400 (b) 40000 (c) 4000
  39. 39.Best estimate of 37 × 67? (a) 2800 (b) 280 (c) 28000
  40. 40.Best estimate of 76 × 36? (a) 3200 (b) 32000 (c) 320

Answer key

  1. 700
  2. 1500
  3. 9000
  4. 3200
  5. 1300
  6. 900
  7. 1200
  8. 2800
  9. 900
  10. 900
  11. 600
  12. 1300
  13. 10000
  14. 4500
  15. 1200
  16. 1000
  17. 1800
  18. 900
  19. 8100
  20. 600
  21. 400
  22. 600
  23. 1500
  24. 6300
  25. 2500
  26. 1300
  27. 1000
  28. 3600
  29. 2500
  30. 1000
  31. 1200
  32. 2000
  33. 1600
  34. 1000
  35. 1200
  36. 6300
  37. 1800
  38. 4000
  39. 2800
  40. 3200

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