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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 932 · 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 44 × 20? (a) 80 (b) 800 (c) 8000
  2. 2.Best estimate of 97 × 12? (a) 1000 (b) 10000 (c) 100
  3. 3.Best estimate of 71 × 23? (a) 14000 (b) 1400 (c) 140
  4. 4.Best estimate of 80 × 36? (a) 3200 (b) 32000 (c) 320
  5. 5.Best estimate of 73 × 30? (a) 2100 (b) 21000 (c) 210
  6. 6.Best estimate of 427 + 572? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 69 × 29? (a) 21000 (b) 210 (c) 2100
  8. 8.Best estimate of 253 + 555? (a) 900 (b) 700 (c) 1100
  9. 9.Best estimate of 70 × 78? (a) 560 (b) 56000 (c) 5600
  10. 10.Best estimate of 29 × 51? (a) 15000 (b) 1500 (c) 150
  11. 11.Best estimate of 704 + 862? (a) 1400 (b) 1600 (c) 1800
  12. 12.Best estimate of 635 + 516? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 482 + 629? (a) 1100 (b) 900 (c) 1300
  14. 14.Best estimate of 86 × 39? (a) 360 (b) 3600 (c) 36000
  15. 15.Best estimate of 17 × 41? (a) 80 (b) 800 (c) 8000
  16. 16.Best estimate of 12 × 17? (a) 2000 (b) 200 (c) 20
  17. 17.Best estimate of 277 + 221? (a) 700 (b) 300 (c) 500
  18. 18.Best estimate of 353 + 552? (a) 800 (b) 1000 (c) 1200
  19. 19.Best estimate of 48 × 39? (a) 20000 (b) 2000 (c) 200
  20. 20.Best estimate of 123 + 536? (a) 600 (b) 800 (c) 400
  21. 21.Best estimate of 706 + 377? (a) 900 (b) 1300 (c) 1100
  22. 22.Best estimate of 588 + 165? (a) 800 (b) 600 (c) 1000
  23. 23.Best estimate of 67 × 56? (a) 42000 (b) 420 (c) 4200
  24. 24.Best estimate of 52 × 78? (a) 4000 (b) 400 (c) 40000
  25. 25.Best estimate of 311 + 777? (a) 1100 (b) 1300 (c) 900
  26. 26.Best estimate of 745 + 815? (a) 1500 (b) 1300 (c) 1700
  27. 27.Best estimate of 778 + 233? (a) 800 (b) 1200 (c) 1000
  28. 28.Best estimate of 59 × 32? (a) 18000 (b) 180 (c) 1800
  29. 29.Best estimate of 60 × 73? (a) 4200 (b) 42000 (c) 420
  30. 30.Best estimate of 18 × 77? (a) 16000 (b) 1600 (c) 160
  31. 31.Best estimate of 61 × 16? (a) 120 (b) 1200 (c) 12000
  32. 32.Best estimate of 196 + 812? (a) 800 (b) 1200 (c) 1000
  33. 33.Best estimate of 810 + 124? (a) 1100 (b) 700 (c) 900
  34. 34.Best estimate of 96 × 14? (a) 100 (b) 10000 (c) 1000
  35. 35.Best estimate of 71 × 33? (a) 21000 (b) 210 (c) 2100
  36. 36.Best estimate of 76 × 37? (a) 320 (b) 32000 (c) 3200
  37. 37.Best estimate of 43 × 81? (a) 32000 (b) 3200 (c) 320
  38. 38.Best estimate of 86 × 31? (a) 27000 (b) 2700 (c) 270
  39. 39.Best estimate of 29 × 56? (a) 1800 (b) 18000 (c) 180
  40. 40.Best estimate of 369 + 131? (a) 300 (b) 700 (c) 500

Answer key

  1. 800
  2. 1000
  3. 1400
  4. 3200
  5. 2100
  6. 1000
  7. 2100
  8. 900
  9. 5600
  10. 1500
  11. 1600
  12. 1100
  13. 1100
  14. 3600
  15. 800
  16. 200
  17. 500
  18. 1000
  19. 2000
  20. 600
  21. 1100
  22. 800
  23. 4200
  24. 4000
  25. 1100
  26. 1500
  27. 1000
  28. 1800
  29. 4200
  30. 1600
  31. 1200
  32. 1000
  33. 900
  34. 1000
  35. 2100
  36. 3200
  37. 3200
  38. 2700
  39. 1800
  40. 500

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