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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 679 · 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 36 × 84? (a) 3200 (b) 32000 (c) 320
  2. 2.Best estimate of 18 × 31? (a) 600 (b) 60 (c) 6000
  3. 3.Best estimate of 797 + 291? (a) 1300 (b) 900 (c) 1100
  4. 4.Best estimate of 22 × 24? (a) 40 (b) 4000 (c) 400
  5. 5.Best estimate of 321 + 472? (a) 800 (b) 600 (c) 1000
  6. 6.Best estimate of 16 × 17? (a) 40 (b) 400 (c) 4000
  7. 7.Best estimate of 149 + 589? (a) 900 (b) 500 (c) 700
  8. 8.Best estimate of 16 × 98? (a) 20000 (b) 200 (c) 2000
  9. 9.Best estimate of 76 × 26? (a) 2400 (b) 240 (c) 24000
  10. 10.Best estimate of 46 × 38? (a) 2000 (b) 200 (c) 20000
  11. 11.Best estimate of 42 × 29? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 143 + 855? (a) 1200 (b) 800 (c) 1000
  13. 13.Best estimate of 40 × 66? (a) 28000 (b) 2800 (c) 280
  14. 14.Best estimate of 722 + 125? (a) 600 (b) 1000 (c) 800
  15. 15.Best estimate of 86 × 63? (a) 5400 (b) 54000 (c) 540
  16. 16.Best estimate of 719 + 218? (a) 700 (b) 1100 (c) 900
  17. 17.Best estimate of 551 + 783? (a) 1600 (b) 1400 (c) 1200
  18. 18.Best estimate of 186 + 613? (a) 1000 (b) 600 (c) 800
  19. 19.Best estimate of 519 + 586? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 376 + 810? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 19 × 62? (a) 1200 (b) 120 (c) 12000
  22. 22.Best estimate of 58 × 66? (a) 420 (b) 4200 (c) 42000
  23. 23.Best estimate of 48 × 67? (a) 350 (b) 3500 (c) 35000
  24. 24.Best estimate of 777 + 419? (a) 1000 (b) 1200 (c) 1400
  25. 25.Best estimate of 231 + 607? (a) 1000 (b) 600 (c) 800
  26. 26.Best estimate of 255 + 295? (a) 400 (b) 600 (c) 800
  27. 27.Best estimate of 140 + 320? (a) 400 (b) 200 (c) 600
  28. 28.Best estimate of 353 + 123? (a) 500 (b) 300 (c) 700
  29. 29.Best estimate of 90 × 96? (a) 90000 (b) 9000 (c) 900
  30. 30.Best estimate of 96 × 73? (a) 7000 (b) 70000 (c) 700
  31. 31.Best estimate of 312 + 230? (a) 700 (b) 300 (c) 500
  32. 32.Best estimate of 124 + 296? (a) 400 (b) 600 (c) 200
  33. 33.Best estimate of 370 + 489? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 46 × 79? (a) 40000 (b) 4000 (c) 400
  35. 35.Best estimate of 29 × 60? (a) 180 (b) 1800 (c) 18000
  36. 36.Best estimate of 243 + 722? (a) 700 (b) 900 (c) 1100
  37. 37.Best estimate of 436 + 164? (a) 600 (b) 400 (c) 800
  38. 38.Best estimate of 24 × 42? (a) 8000 (b) 800 (c) 80
  39. 39.Best estimate of 57 × 33? (a) 180 (b) 18000 (c) 1800
  40. 40.Best estimate of 662 + 696? (a) 1600 (b) 1400 (c) 1200

Answer key

  1. 3200
  2. 600
  3. 1100
  4. 400
  5. 800
  6. 400
  7. 700
  8. 2000
  9. 2400
  10. 2000
  11. 1200
  12. 1000
  13. 2800
  14. 800
  15. 5400
  16. 900
  17. 1400
  18. 800
  19. 1100
  20. 1200
  21. 1200
  22. 4200
  23. 3500
  24. 1200
  25. 800
  26. 600
  27. 400
  28. 500
  29. 9000
  30. 7000
  31. 500
  32. 400
  33. 900
  34. 4000
  35. 1800
  36. 900
  37. 600
  38. 800
  39. 1800
  40. 1400

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