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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 142 · 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 64 × 42? (a) 240 (b) 24000 (c) 2400
  2. 2.Best estimate of 37 × 38? (a) 16000 (b) 1600 (c) 160
  3. 3.Best estimate of 12 × 96? (a) 10000 (b) 100 (c) 1000
  4. 4.Best estimate of 36 × 94? (a) 36000 (b) 3600 (c) 360
  5. 5.Best estimate of 36 × 19? (a) 80 (b) 8000 (c) 800
  6. 6.Best estimate of 39 × 13? (a) 400 (b) 40 (c) 4000
  7. 7.Best estimate of 73 × 60? (a) 42000 (b) 420 (c) 4200
  8. 8.Best estimate of 872 + 338? (a) 1200 (b) 1400 (c) 1000
  9. 9.Best estimate of 420 + 869? (a) 1500 (b) 1100 (c) 1300
  10. 10.Best estimate of 238 + 521? (a) 900 (b) 500 (c) 700
  11. 11.Best estimate of 90 × 74? (a) 63000 (b) 630 (c) 6300
  12. 12.Best estimate of 40 × 68? (a) 28000 (b) 280 (c) 2800
  13. 13.Best estimate of 588 + 488? (a) 1100 (b) 1300 (c) 900
  14. 14.Best estimate of 62 × 84? (a) 4800 (b) 480 (c) 48000
  15. 15.Best estimate of 17 × 13? (a) 200 (b) 2000 (c) 20
  16. 16.Best estimate of 368 + 797? (a) 1000 (b) 1200 (c) 1400
  17. 17.Best estimate of 178 + 652? (a) 900 (b) 700 (c) 1100
  18. 18.Best estimate of 153 + 135? (a) 300 (b) 100 (c) 500
  19. 19.Best estimate of 38 × 77? (a) 3200 (b) 32000 (c) 320
  20. 20.Best estimate of 16 × 62? (a) 12000 (b) 1200 (c) 120
  21. 21.Best estimate of 346 + 267? (a) 800 (b) 600 (c) 400
  22. 22.Best estimate of 90 × 21? (a) 18000 (b) 1800 (c) 180
  23. 23.Best estimate of 56 × 87? (a) 54000 (b) 5400 (c) 540
  24. 24.Best estimate of 431 + 342? (a) 500 (b) 700 (c) 900
  25. 25.Best estimate of 151 + 282? (a) 500 (b) 300 (c) 700
  26. 26.Best estimate of 210 + 582? (a) 600 (b) 800 (c) 1000
  27. 27.Best estimate of 22 × 46? (a) 10000 (b) 1000 (c) 100
  28. 28.Best estimate of 188 + 752? (a) 800 (b) 1200 (c) 1000
  29. 29.Best estimate of 457 + 673? (a) 1200 (b) 1400 (c) 1000
  30. 30.Best estimate of 569 + 771? (a) 1600 (b) 1400 (c) 1200
  31. 31.Best estimate of 223 + 601? (a) 800 (b) 600 (c) 1000
  32. 32.Best estimate of 98 × 31? (a) 300 (b) 3000 (c) 30000
  33. 33.Best estimate of 36 × 49? (a) 200 (b) 2000 (c) 20000
  34. 34.Best estimate of 87 × 46? (a) 45000 (b) 4500 (c) 450
  35. 35.Best estimate of 402 + 418? (a) 600 (b) 800 (c) 1000
  36. 36.Best estimate of 33 × 56? (a) 180 (b) 18000 (c) 1800
  37. 37.Best estimate of 96 × 88? (a) 90000 (b) 9000 (c) 900
  38. 38.Best estimate of 87 × 97? (a) 9000 (b) 90000 (c) 900
  39. 39.Best estimate of 852 + 185? (a) 1100 (b) 1300 (c) 900
  40. 40.Best estimate of 552 + 652? (a) 1100 (b) 1500 (c) 1300

Answer key

  1. 2400
  2. 1600
  3. 1000
  4. 3600
  5. 800
  6. 400
  7. 4200
  8. 1200
  9. 1300
  10. 700
  11. 6300
  12. 2800
  13. 1100
  14. 4800
  15. 200
  16. 1200
  17. 900
  18. 300
  19. 3200
  20. 1200
  21. 600
  22. 1800
  23. 5400
  24. 700
  25. 500
  26. 800
  27. 1000
  28. 1000
  29. 1200
  30. 1400
  31. 800
  32. 3000
  33. 2000
  34. 4500
  35. 800
  36. 1800
  37. 9000
  38. 9000
  39. 1100
  40. 1300

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