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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 303 · 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 83 × 76? (a) 64000 (b) 6400 (c) 640
  2. 2.Best estimate of 68 × 54? (a) 350 (b) 35000 (c) 3500
  3. 3.Best estimate of 58 × 64? (a) 3600 (b) 36000 (c) 360
  4. 4.Best estimate of 93 × 32? (a) 27000 (b) 2700 (c) 270
  5. 5.Best estimate of 14 × 94? (a) 9000 (b) 900 (c) 90
  6. 6.Best estimate of 128 + 540? (a) 400 (b) 600 (c) 800
  7. 7.Best estimate of 178 + 365? (a) 800 (b) 400 (c) 600
  8. 8.Best estimate of 96 × 26? (a) 300 (b) 30000 (c) 3000
  9. 9.Best estimate of 722 + 267? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 30 × 96? (a) 30000 (b) 300 (c) 3000
  11. 11.Best estimate of 199 + 504? (a) 900 (b) 700 (c) 500
  12. 12.Best estimate of 22 × 19? (a) 40 (b) 400 (c) 4000
  13. 13.Best estimate of 72 × 28? (a) 2100 (b) 210 (c) 21000
  14. 14.Best estimate of 37 × 71? (a) 2800 (b) 280 (c) 28000
  15. 15.Best estimate of 48 × 32? (a) 15000 (b) 150 (c) 1500
  16. 16.Best estimate of 239 + 590? (a) 1000 (b) 800 (c) 600
  17. 17.Best estimate of 229 + 190? (a) 600 (b) 200 (c) 400
  18. 18.Best estimate of 516 + 202? (a) 500 (b) 900 (c) 700
  19. 19.Best estimate of 20 × 54? (a) 1000 (b) 100 (c) 10000
  20. 20.Best estimate of 53 × 90? (a) 4500 (b) 45000 (c) 450
  21. 21.Best estimate of 19 × 98? (a) 20000 (b) 2000 (c) 200
  22. 22.Best estimate of 470 + 218? (a) 700 (b) 900 (c) 500
  23. 23.Best estimate of 282 + 269? (a) 400 (b) 600 (c) 800
  24. 24.Best estimate of 24 × 88? (a) 180 (b) 1800 (c) 18000
  25. 25.Best estimate of 79 × 96? (a) 80000 (b) 8000 (c) 800
  26. 26.Best estimate of 31 × 17? (a) 6000 (b) 60 (c) 600
  27. 27.Best estimate of 158 + 206? (a) 200 (b) 400 (c) 600
  28. 28.Best estimate of 72 × 81? (a) 5600 (b) 56000 (c) 560
  29. 29.Best estimate of 52 × 70? (a) 35000 (b) 350 (c) 3500
  30. 30.Best estimate of 330 + 266? (a) 400 (b) 800 (c) 600
  31. 31.Best estimate of 193 + 879? (a) 1100 (b) 900 (c) 1300
  32. 32.Best estimate of 17 × 46? (a) 10000 (b) 100 (c) 1000
  33. 33.Best estimate of 23 × 34? (a) 6000 (b) 600 (c) 60
  34. 34.Best estimate of 151 + 655? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 277 + 737? (a) 1000 (b) 800 (c) 1200
  36. 36.Best estimate of 131 + 228? (a) 100 (b) 300 (c) 500
  37. 37.Best estimate of 16 × 42? (a) 8000 (b) 80 (c) 800
  38. 38.Best estimate of 58 × 46? (a) 300 (b) 30000 (c) 3000
  39. 39.Best estimate of 24 × 36? (a) 8000 (b) 800 (c) 80
  40. 40.Best estimate of 246 + 747? (a) 700 (b) 900 (c) 1100

Answer key

  1. 6400
  2. 3500
  3. 3600
  4. 2700
  5. 900
  6. 600
  7. 600
  8. 3000
  9. 1000
  10. 3000
  11. 700
  12. 400
  13. 2100
  14. 2800
  15. 1500
  16. 800
  17. 400
  18. 700
  19. 1000
  20. 4500
  21. 2000
  22. 700
  23. 600
  24. 1800
  25. 8000
  26. 600
  27. 400
  28. 5600
  29. 3500
  30. 600
  31. 1100
  32. 1000
  33. 600
  34. 900
  35. 1000
  36. 300
  37. 800
  38. 3000
  39. 800
  40. 900

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