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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 193 · 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 20 × 86? (a) 18000 (b) 180 (c) 1800
  2. 2.Best estimate of 130 + 133? (a) 0 (b) 200 (c) 400
  3. 3.Best estimate of 795 + 715? (a) 1300 (b) 1700 (c) 1500
  4. 4.Best estimate of 359 + 726? (a) 1100 (b) 900 (c) 1300
  5. 5.Best estimate of 725 + 532? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 160 + 489? (a) 700 (b) 500 (c) 900
  7. 7.Best estimate of 181 + 422? (a) 600 (b) 800 (c) 400
  8. 8.Best estimate of 148 + 737? (a) 1000 (b) 600 (c) 800
  9. 9.Best estimate of 807 + 220? (a) 1000 (b) 800 (c) 1200
  10. 10.Best estimate of 837 + 275? (a) 1100 (b) 900 (c) 1300
  11. 11.Best estimate of 83 × 21? (a) 160 (b) 16000 (c) 1600
  12. 12.Best estimate of 38 × 27? (a) 12000 (b) 120 (c) 1200
  13. 13.Best estimate of 215 + 308? (a) 500 (b) 700 (c) 300
  14. 14.Best estimate of 18 × 29? (a) 600 (b) 6000 (c) 60
  15. 15.Best estimate of 42 × 43? (a) 1600 (b) 16000 (c) 160
  16. 16.Best estimate of 56 × 36? (a) 24000 (b) 240 (c) 2400
  17. 17.Best estimate of 251 + 440? (a) 700 (b) 500 (c) 900
  18. 18.Best estimate of 53 × 96? (a) 5000 (b) 500 (c) 50000
  19. 19.Best estimate of 662 + 478? (a) 1200 (b) 1400 (c) 1000
  20. 20.Best estimate of 96 × 96? (a) 10000 (b) 100000 (c) 1000
  21. 21.Best estimate of 13 × 67? (a) 70 (b) 700 (c) 7000
  22. 22.Best estimate of 22 × 66? (a) 140 (b) 14000 (c) 1400
  23. 23.Best estimate of 570 + 122? (a) 500 (b) 900 (c) 700
  24. 24.Best estimate of 168 + 829? (a) 800 (b) 1200 (c) 1000
  25. 25.Best estimate of 17 × 43? (a) 80 (b) 8000 (c) 800
  26. 26.Best estimate of 29 × 30? (a) 900 (b) 90 (c) 9000
  27. 27.Best estimate of 705 + 646? (a) 1100 (b) 1300 (c) 1500
  28. 28.Best estimate of 872 + 392? (a) 1300 (b) 1500 (c) 1100
  29. 29.Best estimate of 578 + 324? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 37 × 51? (a) 20000 (b) 200 (c) 2000
  31. 31.Best estimate of 36 × 77? (a) 3200 (b) 320 (c) 32000
  32. 32.Best estimate of 76 × 34? (a) 2400 (b) 24000 (c) 240
  33. 33.Best estimate of 331 + 427? (a) 500 (b) 700 (c) 900
  34. 34.Best estimate of 57 × 82? (a) 48000 (b) 480 (c) 4800
  35. 35.Best estimate of 71 × 19? (a) 14000 (b) 140 (c) 1400
  36. 36.Best estimate of 51 × 51? (a) 25000 (b) 250 (c) 2500
  37. 37.Best estimate of 559 + 183? (a) 800 (b) 600 (c) 1000
  38. 38.Best estimate of 30 × 56? (a) 18000 (b) 1800 (c) 180
  39. 39.Best estimate of 67 × 20? (a) 1400 (b) 14000 (c) 140
  40. 40.Best estimate of 21 × 34? (a) 60 (b) 600 (c) 6000

Answer key

  1. 1800
  2. 200
  3. 1500
  4. 1100
  5. 1200
  6. 700
  7. 600
  8. 800
  9. 1000
  10. 1100
  11. 1600
  12. 1200
  13. 500
  14. 600
  15. 1600
  16. 2400
  17. 700
  18. 5000
  19. 1200
  20. 10000
  21. 700
  22. 1400
  23. 700
  24. 1000
  25. 800
  26. 900
  27. 1300
  28. 1300
  29. 900
  30. 2000
  31. 3200
  32. 2400
  33. 700
  34. 4800
  35. 1400
  36. 2500
  37. 800
  38. 1800
  39. 1400
  40. 600

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