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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 434 · 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 648 + 866? (a) 1300 (b) 1500 (c) 1700
  2. 2.Best estimate of 22 × 76? (a) 160 (b) 1600 (c) 16000
  3. 3.Best estimate of 281 + 875? (a) 1000 (b) 1400 (c) 1200
  4. 4.Best estimate of 747 + 273? (a) 1200 (b) 1000 (c) 800
  5. 5.Best estimate of 23 × 33? (a) 600 (b) 6000 (c) 60
  6. 6.Best estimate of 694 + 444? (a) 1100 (b) 900 (c) 1300
  7. 7.Best estimate of 708 + 616? (a) 1500 (b) 1300 (c) 1100
  8. 8.Best estimate of 47 × 61? (a) 30000 (b) 3000 (c) 300
  9. 9.Best estimate of 172 + 582? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 259 + 502? (a) 1000 (b) 600 (c) 800
  11. 11.Best estimate of 225 + 324? (a) 500 (b) 700 (c) 300
  12. 12.Best estimate of 14 × 26? (a) 3000 (b) 300 (c) 30
  13. 13.Best estimate of 31 × 80? (a) 2400 (b) 240 (c) 24000
  14. 14.Best estimate of 23 × 78? (a) 160 (b) 16000 (c) 1600
  15. 15.Best estimate of 597 + 189? (a) 800 (b) 1000 (c) 600
  16. 16.Best estimate of 22 × 66? (a) 140 (b) 14000 (c) 1400
  17. 17.Best estimate of 248 + 715? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 434 + 265? (a) 500 (b) 700 (c) 900
  19. 19.Best estimate of 36 × 48? (a) 2000 (b) 20000 (c) 200
  20. 20.Best estimate of 34 × 33? (a) 9000 (b) 900 (c) 90
  21. 21.Best estimate of 658 + 473? (a) 1000 (b) 1400 (c) 1200
  22. 22.Best estimate of 56 × 33? (a) 1800 (b) 18000 (c) 180
  23. 23.Best estimate of 31 × 16? (a) 6000 (b) 60 (c) 600
  24. 24.Best estimate of 22 × 44? (a) 80 (b) 8000 (c) 800
  25. 25.Best estimate of 255 + 770? (a) 1100 (b) 1300 (c) 900
  26. 26.Best estimate of 18 × 74? (a) 140 (b) 14000 (c) 1400
  27. 27.Best estimate of 87 × 86? (a) 810 (b) 81000 (c) 8100
  28. 28.Best estimate of 66 × 76? (a) 56000 (b) 560 (c) 5600
  29. 29.Best estimate of 31 × 56? (a) 180 (b) 1800 (c) 18000
  30. 30.Best estimate of 34 × 27? (a) 900 (b) 9000 (c) 90
  31. 31.Best estimate of 51 × 89? (a) 4500 (b) 45000 (c) 450
  32. 32.Best estimate of 182 + 142? (a) 300 (b) 100 (c) 500
  33. 33.Best estimate of 839 + 309? (a) 1100 (b) 900 (c) 1300
  34. 34.Best estimate of 50 × 24? (a) 10000 (b) 100 (c) 1000
  35. 35.Best estimate of 63 × 87? (a) 5400 (b) 54000 (c) 540
  36. 36.Best estimate of 751 + 678? (a) 1700 (b) 1300 (c) 1500
  37. 37.Best estimate of 50 × 81? (a) 40000 (b) 4000 (c) 400
  38. 38.Best estimate of 501 + 393? (a) 700 (b) 900 (c) 1100
  39. 39.Best estimate of 26 × 62? (a) 180 (b) 18000 (c) 1800
  40. 40.Best estimate of 724 + 791? (a) 1700 (b) 1500 (c) 1300

Answer key

  1. 1500
  2. 1600
  3. 1200
  4. 1000
  5. 600
  6. 1100
  7. 1300
  8. 3000
  9. 800
  10. 800
  11. 500
  12. 300
  13. 2400
  14. 1600
  15. 800
  16. 1400
  17. 900
  18. 700
  19. 2000
  20. 900
  21. 1200
  22. 1800
  23. 600
  24. 800
  25. 1100
  26. 1400
  27. 8100
  28. 5600
  29. 1800
  30. 900
  31. 4500
  32. 300
  33. 1100
  34. 1000
  35. 5400
  36. 1500
  37. 4000
  38. 900
  39. 1800
  40. 1500

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