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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 465 · 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 76 × 36? (a) 3200 (b) 32000 (c) 320
  2. 2.Best estimate of 56 × 97? (a) 6000 (b) 60000 (c) 600
  3. 3.Best estimate of 448 + 807? (a) 1000 (b) 1400 (c) 1200
  4. 4.Best estimate of 28 × 29? (a) 9000 (b) 900 (c) 90
  5. 5.Best estimate of 39 × 40? (a) 1600 (b) 16000 (c) 160
  6. 6.Best estimate of 261 + 139? (a) 200 (b) 400 (c) 600
  7. 7.Best estimate of 732 + 329? (a) 1200 (b) 1000 (c) 800
  8. 8.Best estimate of 53 × 53? (a) 2500 (b) 250 (c) 25000
  9. 9.Best estimate of 199 + 341? (a) 700 (b) 500 (c) 300
  10. 10.Best estimate of 29 × 86? (a) 2700 (b) 270 (c) 27000
  11. 11.Best estimate of 50 × 58? (a) 3000 (b) 30000 (c) 300
  12. 12.Best estimate of 62 × 49? (a) 30000 (b) 300 (c) 3000
  13. 13.Best estimate of 331 + 587? (a) 900 (b) 700 (c) 1100
  14. 14.Best estimate of 60 × 97? (a) 600 (b) 60000 (c) 6000
  15. 15.Best estimate of 127 + 565? (a) 900 (b) 500 (c) 700
  16. 16.Best estimate of 42 × 27? (a) 1200 (b) 120 (c) 12000
  17. 17.Best estimate of 434 + 565? (a) 1000 (b) 1200 (c) 800
  18. 18.Best estimate of 868 + 322? (a) 1000 (b) 1400 (c) 1200
  19. 19.Best estimate of 405 + 649? (a) 800 (b) 1000 (c) 1200
  20. 20.Best estimate of 248 + 721? (a) 900 (b) 1100 (c) 700
  21. 21.Best estimate of 49 × 56? (a) 300 (b) 30000 (c) 3000
  22. 22.Best estimate of 540 + 430? (a) 900 (b) 1100 (c) 700
  23. 23.Best estimate of 91 × 33? (a) 2700 (b) 27000 (c) 270
  24. 24.Best estimate of 252 + 238? (a) 300 (b) 700 (c) 500
  25. 25.Best estimate of 26 × 30? (a) 900 (b) 90 (c) 9000
  26. 26.Best estimate of 82 × 80? (a) 6400 (b) 640 (c) 64000
  27. 27.Best estimate of 49 × 61? (a) 30000 (b) 3000 (c) 300
  28. 28.Best estimate of 87 × 33? (a) 2700 (b) 27000 (c) 270
  29. 29.Best estimate of 46 × 54? (a) 250 (b) 25000 (c) 2500
  30. 30.Best estimate of 388 + 870? (a) 1100 (b) 1300 (c) 1500
  31. 31.Best estimate of 155 + 195? (a) 200 (b) 600 (c) 400
  32. 32.Best estimate of 76 × 53? (a) 40000 (b) 400 (c) 4000
  33. 33.Best estimate of 49 × 21? (a) 10000 (b) 1000 (c) 100
  34. 34.Best estimate of 93 × 94? (a) 810 (b) 8100 (c) 81000
  35. 35.Best estimate of 367 + 655? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 34 × 81? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 31 × 64? (a) 1800 (b) 18000 (c) 180
  38. 38.Best estimate of 91 × 53? (a) 45000 (b) 4500 (c) 450
  39. 39.Best estimate of 818 + 720? (a) 1300 (b) 1700 (c) 1500
  40. 40.Best estimate of 206 + 433? (a) 600 (b) 800 (c) 400

Answer key

  1. 3200
  2. 6000
  3. 1200
  4. 900
  5. 1600
  6. 400
  7. 1000
  8. 2500
  9. 500
  10. 2700
  11. 3000
  12. 3000
  13. 900
  14. 6000
  15. 700
  16. 1200
  17. 1000
  18. 1200
  19. 1000
  20. 900
  21. 3000
  22. 900
  23. 2700
  24. 500
  25. 900
  26. 6400
  27. 3000
  28. 2700
  29. 2500
  30. 1300
  31. 400
  32. 4000
  33. 1000
  34. 8100
  35. 1100
  36. 2400
  37. 1800
  38. 4500
  39. 1500
  40. 600

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