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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 32 · 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 793 + 234? (a) 1000 (b) 1200 (c) 800
  2. 2.Best estimate of 181 + 533? (a) 900 (b) 500 (c) 700
  3. 3.Best estimate of 66 × 14? (a) 700 (b) 70 (c) 7000
  4. 4.Best estimate of 66 × 39? (a) 2800 (b) 280 (c) 28000
  5. 5.Best estimate of 488 + 280? (a) 600 (b) 1000 (c) 800
  6. 6.Best estimate of 46 × 26? (a) 15000 (b) 1500 (c) 150
  7. 7.Best estimate of 276 + 451? (a) 1000 (b) 600 (c) 800
  8. 8.Best estimate of 174 + 736? (a) 1100 (b) 900 (c) 700
  9. 9.Best estimate of 123 + 164? (a) 300 (b) 500 (c) 100
  10. 10.Best estimate of 44 × 36? (a) 1600 (b) 16000 (c) 160
  11. 11.Best estimate of 68 × 57? (a) 4200 (b) 420 (c) 42000
  12. 12.Best estimate of 44 × 53? (a) 2000 (b) 20000 (c) 200
  13. 13.Best estimate of 87 × 34? (a) 2700 (b) 27000 (c) 270
  14. 14.Best estimate of 634 + 645? (a) 1200 (b) 1000 (c) 1400
  15. 15.Best estimate of 340 + 310? (a) 600 (b) 400 (c) 800
  16. 16.Best estimate of 32 × 49? (a) 15000 (b) 150 (c) 1500
  17. 17.Best estimate of 42 × 93? (a) 36000 (b) 3600 (c) 360
  18. 18.Best estimate of 24 × 88? (a) 18000 (b) 1800 (c) 180
  19. 19.Best estimate of 430 + 235? (a) 600 (b) 400 (c) 800
  20. 20.Best estimate of 602 + 743? (a) 1500 (b) 1100 (c) 1300
  21. 21.Best estimate of 376 + 816? (a) 1400 (b) 1000 (c) 1200
  22. 22.Best estimate of 74 × 93? (a) 63000 (b) 630 (c) 6300
  23. 23.Best estimate of 92 × 24? (a) 18000 (b) 1800 (c) 180
  24. 24.Best estimate of 68 × 58? (a) 4200 (b) 42000 (c) 420
  25. 25.Best estimate of 581 + 570? (a) 1000 (b) 1200 (c) 1400
  26. 26.Best estimate of 38 × 90? (a) 36000 (b) 3600 (c) 360
  27. 27.Best estimate of 67 × 56? (a) 420 (b) 42000 (c) 4200
  28. 28.Best estimate of 34 × 16? (a) 600 (b) 6000 (c) 60
  29. 29.Best estimate of 647 + 673? (a) 1300 (b) 1500 (c) 1100
  30. 30.Best estimate of 89 × 97? (a) 900 (b) 9000 (c) 90000
  31. 31.Best estimate of 57 × 52? (a) 30000 (b) 300 (c) 3000
  32. 32.Best estimate of 151 + 266? (a) 300 (b) 500 (c) 700
  33. 33.Best estimate of 59 × 54? (a) 3000 (b) 300 (c) 30000
  34. 34.Best estimate of 97 × 68? (a) 70000 (b) 7000 (c) 700
  35. 35.Best estimate of 61 × 36? (a) 240 (b) 24000 (c) 2400
  36. 36.Best estimate of 175 + 576? (a) 1000 (b) 800 (c) 600
  37. 37.Best estimate of 706 + 179? (a) 1100 (b) 700 (c) 900
  38. 38.Best estimate of 91 × 86? (a) 8100 (b) 81000 (c) 810
  39. 39.Best estimate of 42 × 71? (a) 28000 (b) 2800 (c) 280
  40. 40.Best estimate of 24 × 61? (a) 12000 (b) 120 (c) 1200

Answer key

  1. 1000
  2. 700
  3. 700
  4. 2800
  5. 800
  6. 1500
  7. 800
  8. 900
  9. 300
  10. 1600
  11. 4200
  12. 2000
  13. 2700
  14. 1200
  15. 600
  16. 1500
  17. 3600
  18. 1800
  19. 600
  20. 1300
  21. 1200
  22. 6300
  23. 1800
  24. 4200
  25. 1200
  26. 3600
  27. 4200
  28. 600
  29. 1300
  30. 9000
  31. 3000
  32. 500
  33. 3000
  34. 7000
  35. 2400
  36. 800
  37. 900
  38. 8100
  39. 2800
  40. 1200

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