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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 639 · 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 18 × 72? (a) 14000 (b) 140 (c) 1400
  2. 2.Best estimate of 339 + 624? (a) 900 (b) 1100 (c) 700
  3. 3.Best estimate of 457 + 659? (a) 1400 (b) 1000 (c) 1200
  4. 4.Best estimate of 758 + 370? (a) 1000 (b) 1400 (c) 1200
  5. 5.Best estimate of 158 + 817? (a) 1200 (b) 800 (c) 1000
  6. 6.Best estimate of 16 × 20? (a) 400 (b) 4000 (c) 40
  7. 7.Best estimate of 59 × 80? (a) 4800 (b) 480 (c) 48000
  8. 8.Best estimate of 613 + 428? (a) 1200 (b) 1000 (c) 800
  9. 9.Best estimate of 93 × 91? (a) 81000 (b) 8100 (c) 810
  10. 10.Best estimate of 80 × 61? (a) 48000 (b) 480 (c) 4800
  11. 11.Best estimate of 46 × 90? (a) 4500 (b) 450 (c) 45000
  12. 12.Best estimate of 363 + 594? (a) 1200 (b) 1000 (c) 800
  13. 13.Best estimate of 336 + 451? (a) 800 (b) 600 (c) 1000
  14. 14.Best estimate of 97 × 96? (a) 1000 (b) 100000 (c) 10000
  15. 15.Best estimate of 54 × 16? (a) 10000 (b) 100 (c) 1000
  16. 16.Best estimate of 60 × 13? (a) 6000 (b) 60 (c) 600
  17. 17.Best estimate of 77 × 58? (a) 48000 (b) 480 (c) 4800
  18. 18.Best estimate of 797 + 542? (a) 1500 (b) 1100 (c) 1300
  19. 19.Best estimate of 748 + 237? (a) 1100 (b) 700 (c) 900
  20. 20.Best estimate of 50 × 34? (a) 15000 (b) 1500 (c) 150
  21. 21.Best estimate of 542 + 814? (a) 1500 (b) 1100 (c) 1300
  22. 22.Best estimate of 18 × 49? (a) 1000 (b) 10000 (c) 100
  23. 23.Best estimate of 425 + 332? (a) 500 (b) 900 (c) 700
  24. 24.Best estimate of 51 × 13? (a) 5000 (b) 50 (c) 500
  25. 25.Best estimate of 147 + 276? (a) 400 (b) 600 (c) 200
  26. 26.Best estimate of 192 + 857? (a) 1100 (b) 1300 (c) 900
  27. 27.Best estimate of 97 × 47? (a) 50000 (b) 5000 (c) 500
  28. 28.Best estimate of 26 × 96? (a) 300 (b) 3000 (c) 30000
  29. 29.Best estimate of 168 + 744? (a) 900 (b) 700 (c) 1100
  30. 30.Best estimate of 73 × 19? (a) 1400 (b) 14000 (c) 140
  31. 31.Best estimate of 43 × 54? (a) 20000 (b) 2000 (c) 200
  32. 32.Best estimate of 159 + 585? (a) 800 (b) 600 (c) 1000
  33. 33.Best estimate of 218 + 238? (a) 600 (b) 200 (c) 400
  34. 34.Best estimate of 637 + 465? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 184 + 151? (a) 600 (b) 400 (c) 200
  36. 36.Best estimate of 51 × 97? (a) 500 (b) 50000 (c) 5000
  37. 37.Best estimate of 417 + 143? (a) 500 (b) 700 (c) 300
  38. 38.Best estimate of 606 + 194? (a) 1000 (b) 800 (c) 600
  39. 39.Best estimate of 21 × 82? (a) 160 (b) 16000 (c) 1600
  40. 40.Best estimate of 621 + 700? (a) 1100 (b) 1500 (c) 1300

Answer key

  1. 1400
  2. 900
  3. 1200
  4. 1200
  5. 1000
  6. 400
  7. 4800
  8. 1000
  9. 8100
  10. 4800
  11. 4500
  12. 1000
  13. 800
  14. 10000
  15. 1000
  16. 600
  17. 4800
  18. 1300
  19. 900
  20. 1500
  21. 1300
  22. 1000
  23. 700
  24. 500
  25. 400
  26. 1100
  27. 5000
  28. 3000
  29. 900
  30. 1400
  31. 2000
  32. 800
  33. 400
  34. 1100
  35. 400
  36. 5000
  37. 500
  38. 800
  39. 1600
  40. 1300

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