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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 860 · 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 27 × 16? (a) 60 (b) 600 (c) 6000
  2. 2.Best estimate of 339 + 533? (a) 1000 (b) 600 (c) 800
  3. 3.Best estimate of 74 × 73? (a) 49000 (b) 4900 (c) 490
  4. 4.Best estimate of 243 + 683? (a) 900 (b) 1100 (c) 700
  5. 5.Best estimate of 673 + 829? (a) 1700 (b) 1500 (c) 1300
  6. 6.Best estimate of 42 × 81? (a) 32000 (b) 320 (c) 3200
  7. 7.Best estimate of 475 + 469? (a) 1000 (b) 800 (c) 1200
  8. 8.Best estimate of 33 × 94? (a) 2700 (b) 27000 (c) 270
  9. 9.Best estimate of 93 × 96? (a) 9000 (b) 90000 (c) 900
  10. 10.Best estimate of 36 × 76? (a) 3200 (b) 320 (c) 32000
  11. 11.Best estimate of 775 + 163? (a) 800 (b) 1200 (c) 1000
  12. 12.Best estimate of 257 + 551? (a) 700 (b) 900 (c) 1100
  13. 13.Best estimate of 247 + 545? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 711 + 766? (a) 1300 (b) 1700 (c) 1500
  15. 15.Best estimate of 146 + 272? (a) 600 (b) 200 (c) 400
  16. 16.Best estimate of 54 × 90? (a) 45000 (b) 450 (c) 4500
  17. 17.Best estimate of 151 + 838? (a) 1000 (b) 1200 (c) 800
  18. 18.Best estimate of 589 + 334? (a) 1100 (b) 700 (c) 900
  19. 19.Best estimate of 31 × 19? (a) 6000 (b) 600 (c) 60
  20. 20.Best estimate of 57 × 20? (a) 120 (b) 12000 (c) 1200
  21. 21.Best estimate of 579 + 139? (a) 900 (b) 700 (c) 500
  22. 22.Best estimate of 54 × 57? (a) 300 (b) 3000 (c) 30000
  23. 23.Best estimate of 30 × 23? (a) 60 (b) 6000 (c) 600
  24. 24.Best estimate of 60 × 47? (a) 300 (b) 30000 (c) 3000
  25. 25.Best estimate of 279 + 451? (a) 600 (b) 1000 (c) 800
  26. 26.Best estimate of 61 × 61? (a) 3600 (b) 36000 (c) 360
  27. 27.Best estimate of 20 × 56? (a) 120 (b) 12000 (c) 1200
  28. 28.Best estimate of 50 × 30? (a) 15000 (b) 1500 (c) 150
  29. 29.Best estimate of 407 + 815? (a) 1200 (b) 1400 (c) 1000
  30. 30.Best estimate of 36 × 87? (a) 36000 (b) 360 (c) 3600
  31. 31.Best estimate of 70 × 30? (a) 21000 (b) 2100 (c) 210
  32. 32.Best estimate of 56 × 82? (a) 48000 (b) 480 (c) 4800
  33. 33.Best estimate of 58 × 16? (a) 120 (b) 12000 (c) 1200
  34. 34.Best estimate of 12 × 24? (a) 20 (b) 2000 (c) 200
  35. 35.Best estimate of 53 × 13? (a) 500 (b) 50 (c) 5000
  36. 36.Best estimate of 66 × 73? (a) 490 (b) 49000 (c) 4900
  37. 37.Best estimate of 36 × 64? (a) 24000 (b) 2400 (c) 240
  38. 38.Best estimate of 37 × 17? (a) 80 (b) 800 (c) 8000
  39. 39.Best estimate of 339 + 229? (a) 300 (b) 500 (c) 700
  40. 40.Best estimate of 88 × 52? (a) 45000 (b) 4500 (c) 450

Answer key

  1. 600
  2. 800
  3. 4900
  4. 900
  5. 1500
  6. 3200
  7. 1000
  8. 2700
  9. 9000
  10. 3200
  11. 1000
  12. 900
  13. 700
  14. 1500
  15. 400
  16. 4500
  17. 1000
  18. 900
  19. 600
  20. 1200
  21. 700
  22. 3000
  23. 600
  24. 3000
  25. 800
  26. 3600
  27. 1200
  28. 1500
  29. 1200
  30. 3600
  31. 2100
  32. 4800
  33. 1200
  34. 200
  35. 500
  36. 4900
  37. 2400
  38. 800
  39. 500
  40. 4500

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