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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 176 · 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 19 × 37? (a) 8000 (b) 80 (c) 800
  2. 2.Best estimate of 20 × 76? (a) 160 (b) 1600 (c) 16000
  3. 3.Best estimate of 80 × 22? (a) 160 (b) 1600 (c) 16000
  4. 4.Best estimate of 513 + 855? (a) 1400 (b) 1600 (c) 1200
  5. 5.Best estimate of 327 + 637? (a) 700 (b) 900 (c) 1100
  6. 6.Best estimate of 458 + 451? (a) 800 (b) 1200 (c) 1000
  7. 7.Best estimate of 22 × 79? (a) 1600 (b) 16000 (c) 160
  8. 8.Best estimate of 131 + 716? (a) 800 (b) 1000 (c) 600
  9. 9.Best estimate of 436 + 596? (a) 1200 (b) 1000 (c) 800
  10. 10.Best estimate of 78 × 57? (a) 48000 (b) 480 (c) 4800
  11. 11.Best estimate of 57 × 49? (a) 30000 (b) 300 (c) 3000
  12. 12.Best estimate of 569 + 716? (a) 1100 (b) 1500 (c) 1300
  13. 13.Best estimate of 23 × 86? (a) 1800 (b) 18000 (c) 180
  14. 14.Best estimate of 513 + 263? (a) 600 (b) 1000 (c) 800
  15. 15.Best estimate of 61 × 14? (a) 60 (b) 600 (c) 6000
  16. 16.Best estimate of 533 + 829? (a) 1100 (b) 1500 (c) 1300
  17. 17.Best estimate of 644 + 552? (a) 1000 (b) 1200 (c) 1400
  18. 18.Best estimate of 87 × 19? (a) 180 (b) 1800 (c) 18000
  19. 19.Best estimate of 708 + 267? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 432 + 791? (a) 1000 (b) 1200 (c) 1400
  21. 21.Best estimate of 86 × 89? (a) 81000 (b) 810 (c) 8100
  22. 22.Best estimate of 89 × 30? (a) 27000 (b) 270 (c) 2700
  23. 23.Best estimate of 77 × 28? (a) 24000 (b) 2400 (c) 240
  24. 24.Best estimate of 824 + 380? (a) 1400 (b) 1000 (c) 1200
  25. 25.Best estimate of 37 × 58? (a) 24000 (b) 240 (c) 2400
  26. 26.Best estimate of 94 × 86? (a) 8100 (b) 81000 (c) 810
  27. 27.Best estimate of 72 × 20? (a) 140 (b) 1400 (c) 14000
  28. 28.Best estimate of 347 + 764? (a) 1300 (b) 900 (c) 1100
  29. 29.Best estimate of 17 × 81? (a) 16000 (b) 160 (c) 1600
  30. 30.Best estimate of 22 × 44? (a) 800 (b) 8000 (c) 80
  31. 31.Best estimate of 312 + 760? (a) 1300 (b) 900 (c) 1100
  32. 32.Best estimate of 84 × 86? (a) 7200 (b) 720 (c) 72000
  33. 33.Best estimate of 475 + 189? (a) 700 (b) 900 (c) 500
  34. 34.Best estimate of 17 × 64? (a) 1200 (b) 120 (c) 12000
  35. 35.Best estimate of 563 + 654? (a) 1100 (b) 1300 (c) 1500
  36. 36.Best estimate of 80 × 66? (a) 560 (b) 5600 (c) 56000
  37. 37.Best estimate of 94 × 13? (a) 900 (b) 90 (c) 9000
  38. 38.Best estimate of 66 × 36? (a) 28000 (b) 280 (c) 2800
  39. 39.Best estimate of 440 + 448? (a) 600 (b) 1000 (c) 800
  40. 40.Best estimate of 56 × 54? (a) 3000 (b) 300 (c) 30000

Answer key

  1. 800
  2. 1600
  3. 1600
  4. 1400
  5. 900
  6. 1000
  7. 1600
  8. 800
  9. 1000
  10. 4800
  11. 3000
  12. 1300
  13. 1800
  14. 800
  15. 600
  16. 1300
  17. 1200
  18. 1800
  19. 1000
  20. 1200
  21. 8100
  22. 2700
  23. 2400
  24. 1200
  25. 2400
  26. 8100
  27. 1400
  28. 1100
  29. 1600
  30. 800
  31. 1100
  32. 7200
  33. 700
  34. 1200
  35. 1300
  36. 5600
  37. 900
  38. 2800
  39. 800
  40. 3000

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