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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 956 · 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 23 × 36? (a) 80 (b) 800 (c) 8000
  2. 2.Best estimate of 52 × 17? (a) 10000 (b) 1000 (c) 100
  3. 3.Best estimate of 327 + 629? (a) 1100 (b) 900 (c) 700
  4. 4.Best estimate of 293 + 121? (a) 600 (b) 200 (c) 400
  5. 5.Best estimate of 69 × 81? (a) 5600 (b) 56000 (c) 560
  6. 6.Best estimate of 66 × 20? (a) 140 (b) 14000 (c) 1400
  7. 7.Best estimate of 394 + 669? (a) 900 (b) 1100 (c) 1300
  8. 8.Best estimate of 24 × 86? (a) 18000 (b) 180 (c) 1800
  9. 9.Best estimate of 257 + 348? (a) 600 (b) 400 (c) 800
  10. 10.Best estimate of 297 + 824? (a) 1100 (b) 900 (c) 1300
  11. 11.Best estimate of 719 + 837? (a) 1500 (b) 1700 (c) 1300
  12. 12.Best estimate of 72 × 14? (a) 700 (b) 70 (c) 7000
  13. 13.Best estimate of 57 × 16? (a) 1200 (b) 120 (c) 12000
  14. 14.Best estimate of 223 + 501? (a) 900 (b) 500 (c) 700
  15. 15.Best estimate of 682 + 869? (a) 1800 (b) 1400 (c) 1600
  16. 16.Best estimate of 23 × 59? (a) 120 (b) 1200 (c) 12000
  17. 17.Best estimate of 442 + 579? (a) 800 (b) 1200 (c) 1000
  18. 18.Best estimate of 487 + 664? (a) 1400 (b) 1200 (c) 1000
  19. 19.Best estimate of 819 + 880? (a) 1700 (b) 1900 (c) 1500
  20. 20.Best estimate of 736 + 476? (a) 1200 (b) 1000 (c) 1400
  21. 21.Best estimate of 797 + 449? (a) 1200 (b) 1000 (c) 1400
  22. 22.Best estimate of 135 + 594? (a) 500 (b) 700 (c) 900
  23. 23.Best estimate of 837 + 618? (a) 1400 (b) 1200 (c) 1600
  24. 24.Best estimate of 29 × 37? (a) 1200 (b) 120 (c) 12000
  25. 25.Best estimate of 69 × 61? (a) 42000 (b) 420 (c) 4200
  26. 26.Best estimate of 743 + 162? (a) 700 (b) 900 (c) 1100
  27. 27.Best estimate of 265 + 791? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 253 + 220? (a) 700 (b) 500 (c) 300
  29. 29.Best estimate of 43 × 28? (a) 1200 (b) 12000 (c) 120
  30. 30.Best estimate of 23 × 37? (a) 8000 (b) 800 (c) 80
  31. 31.Best estimate of 290 + 185? (a) 300 (b) 700 (c) 500
  32. 32.Best estimate of 444 + 434? (a) 800 (b) 1000 (c) 600
  33. 33.Best estimate of 300 + 294? (a) 600 (b) 800 (c) 400
  34. 34.Best estimate of 28 × 97? (a) 3000 (b) 30000 (c) 300
  35. 35.Best estimate of 57 × 56? (a) 360 (b) 3600 (c) 36000
  36. 36.Best estimate of 56 × 16? (a) 1200 (b) 12000 (c) 120
  37. 37.Best estimate of 189 + 456? (a) 500 (b) 700 (c) 900
  38. 38.Best estimate of 278 + 664? (a) 1200 (b) 800 (c) 1000
  39. 39.Best estimate of 367 + 227? (a) 400 (b) 800 (c) 600
  40. 40.Best estimate of 87 × 51? (a) 4500 (b) 45000 (c) 450

Answer key

  1. 800
  2. 1000
  3. 900
  4. 400
  5. 5600
  6. 1400
  7. 1100
  8. 1800
  9. 600
  10. 1100
  11. 1500
  12. 700
  13. 1200
  14. 700
  15. 1600
  16. 1200
  17. 1000
  18. 1200
  19. 1700
  20. 1200
  21. 1200
  22. 700
  23. 1400
  24. 1200
  25. 4200
  26. 900
  27. 1100
  28. 500
  29. 1200
  30. 800
  31. 500
  32. 800
  33. 600
  34. 3000
  35. 3600
  36. 1200
  37. 700
  38. 1000
  39. 600
  40. 4500

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