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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 361 · 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 76 × 76? (a) 6400 (b) 640 (c) 64000
  2. 2.Best estimate of 46 × 16? (a) 10000 (b) 100 (c) 1000
  3. 3.Best estimate of 22 × 59? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 619 + 584? (a) 1000 (b) 1400 (c) 1200
  5. 5.Best estimate of 285 + 280? (a) 400 (b) 600 (c) 800
  6. 6.Best estimate of 155 + 818? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 83 × 92? (a) 72000 (b) 7200 (c) 720
  8. 8.Best estimate of 386 + 323? (a) 700 (b) 500 (c) 900
  9. 9.Best estimate of 531 + 334? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 67 × 97? (a) 7000 (b) 70000 (c) 700
  11. 11.Best estimate of 777 + 170? (a) 1200 (b) 800 (c) 1000
  12. 12.Best estimate of 44 × 67? (a) 28000 (b) 280 (c) 2800
  13. 13.Best estimate of 38 × 20? (a) 80 (b) 8000 (c) 800
  14. 14.Best estimate of 46 × 76? (a) 4000 (b) 40000 (c) 400
  15. 15.Best estimate of 677 + 555? (a) 1300 (b) 1500 (c) 1100
  16. 16.Best estimate of 879 + 138? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 661 + 205? (a) 900 (b) 1100 (c) 700
  18. 18.Best estimate of 787 + 161? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 880 + 176? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 12 × 40? (a) 4000 (b) 400 (c) 40
  21. 21.Best estimate of 77 × 46? (a) 40000 (b) 400 (c) 4000
  22. 22.Best estimate of 820 + 463? (a) 1100 (b) 1500 (c) 1300
  23. 23.Best estimate of 37 × 96? (a) 4000 (b) 400 (c) 40000
  24. 24.Best estimate of 665 + 330? (a) 1000 (b) 800 (c) 1200
  25. 25.Best estimate of 790 + 199? (a) 1000 (b) 800 (c) 1200
  26. 26.Best estimate of 28 × 32? (a) 90 (b) 9000 (c) 900
  27. 27.Best estimate of 851 + 125? (a) 1000 (b) 1200 (c) 800
  28. 28.Best estimate of 303 + 830? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 47 × 29? (a) 15000 (b) 150 (c) 1500
  30. 30.Best estimate of 97 × 40? (a) 400 (b) 4000 (c) 40000
  31. 31.Best estimate of 508 + 462? (a) 800 (b) 1200 (c) 1000
  32. 32.Best estimate of 142 + 714? (a) 800 (b) 1000 (c) 600
  33. 33.Best estimate of 577 + 798? (a) 1600 (b) 1400 (c) 1200
  34. 34.Best estimate of 213 + 757? (a) 1000 (b) 1200 (c) 800
  35. 35.Best estimate of 379 + 863? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 193 + 398? (a) 600 (b) 800 (c) 400
  37. 37.Best estimate of 88 × 89? (a) 8100 (b) 810 (c) 81000
  38. 38.Best estimate of 33 × 74? (a) 2100 (b) 21000 (c) 210
  39. 39.Best estimate of 218 + 121? (a) 300 (b) 100 (c) 500
  40. 40.Best estimate of 781 + 149? (a) 700 (b) 900 (c) 1100

Answer key

  1. 6400
  2. 1000
  3. 1200
  4. 1200
  5. 600
  6. 1000
  7. 7200
  8. 700
  9. 800
  10. 7000
  11. 1000
  12. 2800
  13. 800
  14. 4000
  15. 1300
  16. 1000
  17. 900
  18. 1000
  19. 1100
  20. 400
  21. 4000
  22. 1300
  23. 4000
  24. 1000
  25. 1000
  26. 900
  27. 1000
  28. 1100
  29. 1500
  30. 4000
  31. 1000
  32. 800
  33. 1400
  34. 1000
  35. 1300
  36. 600
  37. 8100
  38. 2100
  39. 300
  40. 900

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