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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 312 · 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 729 + 301? (a) 1200 (b) 800 (c) 1000
  2. 2.Best estimate of 521 + 713? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 781 + 643? (a) 1600 (b) 1200 (c) 1400
  4. 4.Best estimate of 575 + 831? (a) 1200 (b) 1400 (c) 1600
  5. 5.Best estimate of 412 + 644? (a) 1000 (b) 1200 (c) 800
  6. 6.Best estimate of 30 × 43? (a) 12000 (b) 120 (c) 1200
  7. 7.Best estimate of 58 × 42? (a) 2400 (b) 24000 (c) 240
  8. 8.Best estimate of 76 × 80? (a) 6400 (b) 64000 (c) 640
  9. 9.Best estimate of 638 + 526? (a) 1300 (b) 1100 (c) 900
  10. 10.Best estimate of 92 × 81? (a) 72000 (b) 720 (c) 7200
  11. 11.Best estimate of 173 + 791? (a) 800 (b) 1200 (c) 1000
  12. 12.Best estimate of 76 × 41? (a) 320 (b) 32000 (c) 3200
  13. 13.Best estimate of 28 × 86? (a) 27000 (b) 270 (c) 2700
  14. 14.Best estimate of 92 × 40? (a) 360 (b) 36000 (c) 3600
  15. 15.Best estimate of 532 + 540? (a) 800 (b) 1200 (c) 1000
  16. 16.Best estimate of 34 × 36? (a) 120 (b) 1200 (c) 12000
  17. 17.Best estimate of 54 × 93? (a) 4500 (b) 45000 (c) 450
  18. 18.Best estimate of 63 × 77? (a) 4800 (b) 48000 (c) 480
  19. 19.Best estimate of 47 × 62? (a) 3000 (b) 30000 (c) 300
  20. 20.Best estimate of 224 + 120? (a) 300 (b) 100 (c) 500
  21. 21.Best estimate of 36 × 38? (a) 16000 (b) 1600 (c) 160
  22. 22.Best estimate of 38 × 20? (a) 8000 (b) 800 (c) 80
  23. 23.Best estimate of 145 + 449? (a) 300 (b) 700 (c) 500
  24. 24.Best estimate of 702 + 351? (a) 1100 (b) 1300 (c) 900
  25. 25.Best estimate of 63 × 80? (a) 4800 (b) 480 (c) 48000
  26. 26.Best estimate of 37 × 50? (a) 2000 (b) 20000 (c) 200
  27. 27.Best estimate of 131 + 361? (a) 700 (b) 300 (c) 500
  28. 28.Best estimate of 96 × 90? (a) 9000 (b) 90000 (c) 900
  29. 29.Best estimate of 308 + 123? (a) 400 (b) 200 (c) 600
  30. 30.Best estimate of 840 + 168? (a) 800 (b) 1200 (c) 1000
  31. 31.Best estimate of 639 + 611? (a) 1400 (b) 1000 (c) 1200
  32. 32.Best estimate of 179 + 134? (a) 500 (b) 100 (c) 300
  33. 33.Best estimate of 616 + 759? (a) 1600 (b) 1400 (c) 1200
  34. 34.Best estimate of 660 + 202? (a) 700 (b) 900 (c) 1100
  35. 35.Best estimate of 131 + 726? (a) 1000 (b) 800 (c) 600
  36. 36.Best estimate of 285 + 300? (a) 800 (b) 400 (c) 600
  37. 37.Best estimate of 156 + 741? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 46 × 37? (a) 2000 (b) 200 (c) 20000
  39. 39.Best estimate of 133 + 258? (a) 600 (b) 400 (c) 200
  40. 40.Best estimate of 572 + 730? (a) 1500 (b) 1300 (c) 1100

Answer key

  1. 1000
  2. 1200
  3. 1400
  4. 1400
  5. 1000
  6. 1200
  7. 2400
  8. 6400
  9. 1100
  10. 7200
  11. 1000
  12. 3200
  13. 2700
  14. 3600
  15. 1000
  16. 1200
  17. 4500
  18. 4800
  19. 3000
  20. 300
  21. 1600
  22. 800
  23. 500
  24. 1100
  25. 4800
  26. 2000
  27. 500
  28. 9000
  29. 400
  30. 1000
  31. 1200
  32. 300
  33. 1400
  34. 900
  35. 800
  36. 600
  37. 900
  38. 2000
  39. 400
  40. 1300

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