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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 766 · 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 20 × 26? (a) 600 (b) 6000 (c) 60
  2. 2.Best estimate of 48 × 74? (a) 3500 (b) 35000 (c) 350
  3. 3.Best estimate of 683 + 816? (a) 1300 (b) 1500 (c) 1700
  4. 4.Best estimate of 28 × 68? (a) 210 (b) 21000 (c) 2100
  5. 5.Best estimate of 689 + 279? (a) 1000 (b) 1200 (c) 800
  6. 6.Best estimate of 90 × 21? (a) 180 (b) 18000 (c) 1800
  7. 7.Best estimate of 31 × 12? (a) 300 (b) 3000 (c) 30
  8. 8.Best estimate of 784 + 280? (a) 900 (b) 1100 (c) 1300
  9. 9.Best estimate of 62 × 27? (a) 18000 (b) 180 (c) 1800
  10. 10.Best estimate of 98 × 78? (a) 80000 (b) 8000 (c) 800
  11. 11.Best estimate of 48 × 21? (a) 1000 (b) 100 (c) 10000
  12. 12.Best estimate of 93 × 23? (a) 1800 (b) 18000 (c) 180
  13. 13.Best estimate of 59 × 69? (a) 420 (b) 42000 (c) 4200
  14. 14.Best estimate of 54 × 71? (a) 35000 (b) 3500 (c) 350
  15. 15.Best estimate of 530 + 278? (a) 800 (b) 600 (c) 1000
  16. 16.Best estimate of 39 × 81? (a) 32000 (b) 320 (c) 3200
  17. 17.Best estimate of 144 + 343? (a) 200 (b) 400 (c) 600
  18. 18.Best estimate of 613 + 137? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 806 + 696? (a) 1300 (b) 1500 (c) 1700
  20. 20.Best estimate of 63 × 47? (a) 30000 (b) 3000 (c) 300
  21. 21.Best estimate of 870 + 254? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 841 + 715? (a) 1700 (b) 1500 (c) 1300
  23. 23.Best estimate of 266 + 484? (a) 1000 (b) 600 (c) 800
  24. 24.Best estimate of 76 × 48? (a) 400 (b) 40000 (c) 4000
  25. 25.Best estimate of 27 × 70? (a) 21000 (b) 2100 (c) 210
  26. 26.Best estimate of 265 + 758? (a) 1300 (b) 1100 (c) 900
  27. 27.Best estimate of 91 × 50? (a) 45000 (b) 450 (c) 4500
  28. 28.Best estimate of 67 × 36? (a) 28000 (b) 2800 (c) 280
  29. 29.Best estimate of 779 + 666? (a) 1300 (b) 1700 (c) 1500
  30. 30.Best estimate of 482 + 126? (a) 800 (b) 600 (c) 400
  31. 31.Best estimate of 82 × 40? (a) 32000 (b) 3200 (c) 320
  32. 32.Best estimate of 52 × 71? (a) 350 (b) 35000 (c) 3500
  33. 33.Best estimate of 344 + 669? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 28 × 26? (a) 9000 (b) 900 (c) 90
  35. 35.Best estimate of 651 + 278? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 26 × 96? (a) 30000 (b) 300 (c) 3000
  37. 37.Best estimate of 480 + 428? (a) 1100 (b) 900 (c) 700
  38. 38.Best estimate of 137 + 615? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 64 × 96? (a) 6000 (b) 600 (c) 60000
  40. 40.Best estimate of 139 + 869? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 600
  2. 3500
  3. 1500
  4. 2100
  5. 1000
  6. 1800
  7. 300
  8. 1100
  9. 1800
  10. 8000
  11. 1000
  12. 1800
  13. 4200
  14. 3500
  15. 800
  16. 3200
  17. 400
  18. 700
  19. 1500
  20. 3000
  21. 1200
  22. 1500
  23. 800
  24. 4000
  25. 2100
  26. 1100
  27. 4500
  28. 2800
  29. 1500
  30. 600
  31. 3200
  32. 3500
  33. 1000
  34. 900
  35. 1000
  36. 3000
  37. 900
  38. 700
  39. 6000
  40. 1000

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