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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 920 · 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 86 × 29? (a) 27000 (b) 2700 (c) 270
  2. 2.Best estimate of 442 + 425? (a) 1000 (b) 800 (c) 600
  3. 3.Best estimate of 73 × 26? (a) 2100 (b) 21000 (c) 210
  4. 4.Best estimate of 14 × 96? (a) 10000 (b) 1000 (c) 100
  5. 5.Best estimate of 82 × 80? (a) 6400 (b) 640 (c) 64000
  6. 6.Best estimate of 181 + 625? (a) 1000 (b) 800 (c) 600
  7. 7.Best estimate of 278 + 792? (a) 900 (b) 1100 (c) 1300
  8. 8.Best estimate of 28 × 56? (a) 1800 (b) 180 (c) 18000
  9. 9.Best estimate of 417 + 321? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 528 + 124? (a) 400 (b) 800 (c) 600
  11. 11.Best estimate of 207 + 479? (a) 700 (b) 500 (c) 900
  12. 12.Best estimate of 538 + 596? (a) 900 (b) 1100 (c) 1300
  13. 13.Best estimate of 874 + 562? (a) 1300 (b) 1500 (c) 1700
  14. 14.Best estimate of 97 × 78? (a) 80000 (b) 800 (c) 8000
  15. 15.Best estimate of 215 + 185? (a) 200 (b) 400 (c) 600
  16. 16.Best estimate of 39 × 77? (a) 32000 (b) 320 (c) 3200
  17. 17.Best estimate of 133 + 580? (a) 500 (b) 900 (c) 700
  18. 18.Best estimate of 50 × 78? (a) 40000 (b) 4000 (c) 400
  19. 19.Best estimate of 485 + 554? (a) 1100 (b) 1300 (c) 900
  20. 20.Best estimate of 89 × 47? (a) 4500 (b) 45000 (c) 450
  21. 21.Best estimate of 372 + 365? (a) 800 (b) 600 (c) 1000
  22. 22.Best estimate of 571 + 165? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 526 + 700? (a) 1000 (b) 1200 (c) 1400
  24. 24.Best estimate of 173 + 259? (a) 700 (b) 300 (c) 500
  25. 25.Best estimate of 826 + 856? (a) 1500 (b) 1900 (c) 1700
  26. 26.Best estimate of 125 + 563? (a) 700 (b) 900 (c) 500
  27. 27.Best estimate of 13 × 16? (a) 20 (b) 2000 (c) 200
  28. 28.Best estimate of 24 × 61? (a) 12000 (b) 1200 (c) 120
  29. 29.Best estimate of 305 + 808? (a) 900 (b) 1100 (c) 1300
  30. 30.Best estimate of 14 × 49? (a) 5000 (b) 500 (c) 50
  31. 31.Best estimate of 48 × 71? (a) 350 (b) 35000 (c) 3500
  32. 32.Best estimate of 56 × 38? (a) 2400 (b) 240 (c) 24000
  33. 33.Best estimate of 385 + 724? (a) 900 (b) 1100 (c) 1300
  34. 34.Best estimate of 130 + 138? (a) 400 (b) 200 (c) 0
  35. 35.Best estimate of 414 + 360? (a) 800 (b) 1000 (c) 600
  36. 36.Best estimate of 204 + 364? (a) 800 (b) 400 (c) 600
  37. 37.Best estimate of 870 + 317? (a) 1000 (b) 1400 (c) 1200
  38. 38.Best estimate of 87 × 41? (a) 3600 (b) 360 (c) 36000
  39. 39.Best estimate of 90 × 70? (a) 6300 (b) 630 (c) 63000
  40. 40.Best estimate of 400 + 759? (a) 1200 (b) 1400 (c) 1000

Answer key

  1. 2700
  2. 800
  3. 2100
  4. 1000
  5. 6400
  6. 800
  7. 1100
  8. 1800
  9. 700
  10. 600
  11. 700
  12. 1100
  13. 1500
  14. 8000
  15. 400
  16. 3200
  17. 700
  18. 4000
  19. 1100
  20. 4500
  21. 800
  22. 800
  23. 1200
  24. 500
  25. 1700
  26. 700
  27. 200
  28. 1200
  29. 1100
  30. 500
  31. 3500
  32. 2400
  33. 1100
  34. 200
  35. 800
  36. 600
  37. 1200
  38. 3600
  39. 6300
  40. 1200

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