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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 342 · 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 32 × 30? (a) 90 (b) 9000 (c) 900
  2. 2.Best estimate of 286 + 483? (a) 1000 (b) 600 (c) 800
  3. 3.Best estimate of 41 × 84? (a) 320 (b) 3200 (c) 32000
  4. 4.Best estimate of 91 × 20? (a) 18000 (b) 180 (c) 1800
  5. 5.Best estimate of 17 × 26? (a) 600 (b) 60 (c) 6000
  6. 6.Best estimate of 456 + 743? (a) 1000 (b) 1200 (c) 1400
  7. 7.Best estimate of 36 × 17? (a) 800 (b) 8000 (c) 80
  8. 8.Best estimate of 58 × 98? (a) 600 (b) 6000 (c) 60000
  9. 9.Best estimate of 763 + 453? (a) 1300 (b) 1500 (c) 1100
  10. 10.Best estimate of 391 + 841? (a) 1200 (b) 1400 (c) 1000
  11. 11.Best estimate of 560 + 248? (a) 800 (b) 600 (c) 1000
  12. 12.Best estimate of 21 × 29? (a) 60 (b) 600 (c) 6000
  13. 13.Best estimate of 68 × 38? (a) 2800 (b) 280 (c) 28000
  14. 14.Best estimate of 135 + 496? (a) 400 (b) 600 (c) 800
  15. 15.Best estimate of 28 × 52? (a) 1500 (b) 15000 (c) 150
  16. 16.Best estimate of 33 × 60? (a) 180 (b) 1800 (c) 18000
  17. 17.Best estimate of 301 + 847? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 23 × 37? (a) 8000 (b) 80 (c) 800
  19. 19.Best estimate of 87 × 76? (a) 7200 (b) 72000 (c) 720
  20. 20.Best estimate of 418 + 452? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 77 × 23? (a) 1600 (b) 16000 (c) 160
  22. 22.Best estimate of 138 + 788? (a) 700 (b) 900 (c) 1100
  23. 23.Best estimate of 264 + 139? (a) 200 (b) 600 (c) 400
  24. 24.Best estimate of 186 + 540? (a) 700 (b) 900 (c) 500
  25. 25.Best estimate of 76 × 81? (a) 6400 (b) 64000 (c) 640
  26. 26.Best estimate of 19 × 33? (a) 600 (b) 6000 (c) 60
  27. 27.Best estimate of 56 × 68? (a) 420 (b) 42000 (c) 4200
  28. 28.Best estimate of 641 + 691? (a) 1500 (b) 1100 (c) 1300
  29. 29.Best estimate of 22 × 78? (a) 1600 (b) 16000 (c) 160
  30. 30.Best estimate of 46 × 47? (a) 250 (b) 25000 (c) 2500
  31. 31.Best estimate of 53 × 56? (a) 30000 (b) 3000 (c) 300
  32. 32.Best estimate of 56 × 76? (a) 480 (b) 4800 (c) 48000
  33. 33.Best estimate of 66 × 23? (a) 1400 (b) 140 (c) 14000
  34. 34.Best estimate of 56 × 61? (a) 36000 (b) 360 (c) 3600
  35. 35.Best estimate of 82 × 93? (a) 720 (b) 7200 (c) 72000
  36. 36.Best estimate of 155 + 184? (a) 600 (b) 200 (c) 400
  37. 37.Best estimate of 56 × 94? (a) 5400 (b) 54000 (c) 540
  38. 38.Best estimate of 549 + 270? (a) 800 (b) 600 (c) 1000
  39. 39.Best estimate of 96 × 18? (a) 2000 (b) 200 (c) 20000
  40. 40.Best estimate of 56 × 23? (a) 120 (b) 1200 (c) 12000

Answer key

  1. 900
  2. 800
  3. 3200
  4. 1800
  5. 600
  6. 1200
  7. 800
  8. 6000
  9. 1300
  10. 1200
  11. 800
  12. 600
  13. 2800
  14. 600
  15. 1500
  16. 1800
  17. 1100
  18. 800
  19. 7200
  20. 900
  21. 1600
  22. 900
  23. 400
  24. 700
  25. 6400
  26. 600
  27. 4200
  28. 1300
  29. 1600
  30. 2500
  31. 3000
  32. 4800
  33. 1400
  34. 3600
  35. 7200
  36. 400
  37. 5400
  38. 800
  39. 2000
  40. 1200

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