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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 568 · 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 90 × 64? (a) 5400 (b) 54000 (c) 540
  2. 2.Best estimate of 584 + 610? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 26 × 71? (a) 21000 (b) 2100 (c) 210
  4. 4.Best estimate of 37 × 57? (a) 240 (b) 2400 (c) 24000
  5. 5.Best estimate of 314 + 238? (a) 500 (b) 300 (c) 700
  6. 6.Best estimate of 21 × 42? (a) 80 (b) 800 (c) 8000
  7. 7.Best estimate of 314 + 731? (a) 1200 (b) 1000 (c) 800
  8. 8.Best estimate of 51 × 98? (a) 5000 (b) 500 (c) 50000
  9. 9.Best estimate of 24 × 59? (a) 1200 (b) 12000 (c) 120
  10. 10.Best estimate of 24 × 68? (a) 140 (b) 14000 (c) 1400
  11. 11.Best estimate of 63 × 20? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 710 + 607? (a) 1100 (b) 1500 (c) 1300
  13. 13.Best estimate of 77 × 47? (a) 40000 (b) 400 (c) 4000
  14. 14.Best estimate of 98 × 66? (a) 70000 (b) 700 (c) 7000
  15. 15.Best estimate of 310 + 553? (a) 900 (b) 1100 (c) 700
  16. 16.Best estimate of 49 × 29? (a) 15000 (b) 150 (c) 1500
  17. 17.Best estimate of 33 × 33? (a) 900 (b) 9000 (c) 90
  18. 18.Best estimate of 26 × 33? (a) 9000 (b) 90 (c) 900
  19. 19.Best estimate of 12 × 39? (a) 40 (b) 400 (c) 4000
  20. 20.Best estimate of 816 + 516? (a) 1100 (b) 1300 (c) 1500
  21. 21.Best estimate of 329 + 144? (a) 600 (b) 200 (c) 400
  22. 22.Best estimate of 33 × 96? (a) 30000 (b) 3000 (c) 300
  23. 23.Best estimate of 29 × 74? (a) 21000 (b) 210 (c) 2100
  24. 24.Best estimate of 18 × 70? (a) 1400 (b) 14000 (c) 140
  25. 25.Best estimate of 249 + 584? (a) 600 (b) 1000 (c) 800
  26. 26.Best estimate of 448 + 391? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 339 + 779? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 64 × 78? (a) 48000 (b) 4800 (c) 480
  29. 29.Best estimate of 636 + 292? (a) 700 (b) 1100 (c) 900
  30. 30.Best estimate of 76 × 74? (a) 56000 (b) 5600 (c) 560
  31. 31.Best estimate of 731 + 592? (a) 1100 (b) 1500 (c) 1300
  32. 32.Best estimate of 74 × 22? (a) 1400 (b) 14000 (c) 140
  33. 33.Best estimate of 416 + 369? (a) 600 (b) 1000 (c) 800
  34. 34.Best estimate of 91 × 60? (a) 5400 (b) 54000 (c) 540
  35. 35.Best estimate of 92 × 94? (a) 8100 (b) 81000 (c) 810
  36. 36.Best estimate of 813 + 197? (a) 800 (b) 1200 (c) 1000
  37. 37.Best estimate of 194 + 323? (a) 700 (b) 300 (c) 500
  38. 38.Best estimate of 59 × 16? (a) 1200 (b) 120 (c) 12000
  39. 39.Best estimate of 177 + 569? (a) 1000 (b) 800 (c) 600
  40. 40.Best estimate of 62 × 36? (a) 2400 (b) 24000 (c) 240

Answer key

  1. 5400
  2. 1200
  3. 2100
  4. 2400
  5. 500
  6. 800
  7. 1000
  8. 5000
  9. 1200
  10. 1400
  11. 1200
  12. 1300
  13. 4000
  14. 7000
  15. 900
  16. 1500
  17. 900
  18. 900
  19. 400
  20. 1300
  21. 400
  22. 3000
  23. 2100
  24. 1400
  25. 800
  26. 800
  27. 1100
  28. 4800
  29. 900
  30. 5600
  31. 1300
  32. 1400
  33. 800
  34. 5400
  35. 8100
  36. 1000
  37. 500
  38. 1200
  39. 800
  40. 2400

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