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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 47 · 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 97 × 66? (a) 7000 (b) 70000 (c) 700
  2. 2.Best estimate of 86 × 12? (a) 9000 (b) 90 (c) 900
  3. 3.Best estimate of 59 × 28? (a) 18000 (b) 180 (c) 1800
  4. 4.Best estimate of 327 + 772? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 57 × 66? (a) 420 (b) 4200 (c) 42000
  6. 6.Best estimate of 541 + 383? (a) 1100 (b) 900 (c) 700
  7. 7.Best estimate of 559 + 217? (a) 800 (b) 600 (c) 1000
  8. 8.Best estimate of 682 + 147? (a) 800 (b) 1000 (c) 600
  9. 9.Best estimate of 86 × 53? (a) 450 (b) 4500 (c) 45000
  10. 10.Best estimate of 47 × 31? (a) 1500 (b) 15000 (c) 150
  11. 11.Best estimate of 616 + 788? (a) 1200 (b) 1600 (c) 1400
  12. 12.Best estimate of 732 + 803? (a) 1700 (b) 1300 (c) 1500
  13. 13.Best estimate of 28 × 42? (a) 120 (b) 12000 (c) 1200
  14. 14.Best estimate of 535 + 146? (a) 600 (b) 400 (c) 800
  15. 15.Best estimate of 516 + 317? (a) 600 (b) 800 (c) 1000
  16. 16.Best estimate of 794 + 195? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 69 × 38? (a) 2800 (b) 28000 (c) 280
  18. 18.Best estimate of 88 × 23? (a) 1800 (b) 180 (c) 18000
  19. 19.Best estimate of 89 × 77? (a) 72000 (b) 7200 (c) 720
  20. 20.Best estimate of 256 + 358? (a) 700 (b) 900 (c) 500
  21. 21.Best estimate of 722 + 452? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 349 + 646? (a) 900 (b) 1100 (c) 700
  23. 23.Best estimate of 19 × 26? (a) 6000 (b) 600 (c) 60
  24. 24.Best estimate of 783 + 765? (a) 1600 (b) 1400 (c) 1800
  25. 25.Best estimate of 90 × 30? (a) 270 (b) 27000 (c) 2700
  26. 26.Best estimate of 53 × 44? (a) 2000 (b) 20000 (c) 200
  27. 27.Best estimate of 474 + 144? (a) 600 (b) 400 (c) 800
  28. 28.Best estimate of 31 × 32? (a) 90 (b) 900 (c) 9000
  29. 29.Best estimate of 764 + 867? (a) 1900 (b) 1700 (c) 1500
  30. 30.Best estimate of 189 + 337? (a) 300 (b) 700 (c) 500
  31. 31.Best estimate of 838 + 511? (a) 1100 (b) 1500 (c) 1300
  32. 32.Best estimate of 56 × 91? (a) 5400 (b) 54000 (c) 540
  33. 33.Best estimate of 609 + 283? (a) 700 (b) 1100 (c) 900
  34. 34.Best estimate of 53 × 91? (a) 4500 (b) 450 (c) 45000
  35. 35.Best estimate of 702 + 453? (a) 1000 (b) 1200 (c) 1400
  36. 36.Best estimate of 69 × 18? (a) 14000 (b) 1400 (c) 140
  37. 37.Best estimate of 254 + 121? (a) 400 (b) 200 (c) 600
  38. 38.Best estimate of 16 × 36? (a) 8000 (b) 800 (c) 80
  39. 39.Best estimate of 19 × 78? (a) 16000 (b) 1600 (c) 160
  40. 40.Best estimate of 30 × 56? (a) 1800 (b) 180 (c) 18000

Answer key

  1. 7000
  2. 900
  3. 1800
  4. 1100
  5. 4200
  6. 900
  7. 800
  8. 800
  9. 4500
  10. 1500
  11. 1400
  12. 1500
  13. 1200
  14. 600
  15. 800
  16. 1000
  17. 2800
  18. 1800
  19. 7200
  20. 700
  21. 1200
  22. 900
  23. 600
  24. 1600
  25. 2700
  26. 2000
  27. 600
  28. 900
  29. 1700
  30. 500
  31. 1300
  32. 5400
  33. 900
  34. 4500
  35. 1200
  36. 1400
  37. 400
  38. 800
  39. 1600
  40. 1800

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