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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 716 · 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 158 + 506? (a) 900 (b) 700 (c) 500
  2. 2.Best estimate of 31 × 71? (a) 21000 (b) 2100 (c) 210
  3. 3.Best estimate of 33 × 76? (a) 24000 (b) 240 (c) 2400
  4. 4.Best estimate of 594 + 327? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 838 + 787? (a) 1400 (b) 1600 (c) 1800
  6. 6.Best estimate of 51 × 30? (a) 15000 (b) 150 (c) 1500
  7. 7.Best estimate of 70 × 64? (a) 4200 (b) 420 (c) 42000
  8. 8.Best estimate of 76 × 49? (a) 400 (b) 4000 (c) 40000
  9. 9.Best estimate of 581 + 153? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 209 + 379? (a) 800 (b) 600 (c) 400
  11. 11.Best estimate of 32 × 53? (a) 150 (b) 15000 (c) 1500
  12. 12.Best estimate of 46 × 96? (a) 5000 (b) 50000 (c) 500
  13. 13.Best estimate of 91 × 37? (a) 3600 (b) 36000 (c) 360
  14. 14.Best estimate of 92 × 39? (a) 3600 (b) 360 (c) 36000
  15. 15.Best estimate of 82 × 28? (a) 2400 (b) 24000 (c) 240
  16. 16.Best estimate of 20 × 34? (a) 600 (b) 60 (c) 6000
  17. 17.Best estimate of 833 + 629? (a) 1200 (b) 1400 (c) 1600
  18. 18.Best estimate of 87 × 96? (a) 90000 (b) 9000 (c) 900
  19. 19.Best estimate of 688 + 132? (a) 800 (b) 1000 (c) 600
  20. 20.Best estimate of 363 + 342? (a) 700 (b) 500 (c) 900
  21. 21.Best estimate of 69 × 66? (a) 4900 (b) 49000 (c) 490
  22. 22.Best estimate of 296 + 472? (a) 800 (b) 600 (c) 1000
  23. 23.Best estimate of 629 + 669? (a) 1300 (b) 1500 (c) 1100
  24. 24.Best estimate of 705 + 228? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 132 + 470? (a) 800 (b) 600 (c) 400
  26. 26.Best estimate of 13 × 72? (a) 7000 (b) 70 (c) 700
  27. 27.Best estimate of 63 × 19? (a) 1200 (b) 120 (c) 12000
  28. 28.Best estimate of 40 × 44? (a) 160 (b) 16000 (c) 1600
  29. 29.Best estimate of 332 + 657? (a) 1000 (b) 800 (c) 1200
  30. 30.Best estimate of 23 × 76? (a) 16000 (b) 1600 (c) 160
  31. 31.Best estimate of 17 × 84? (a) 16000 (b) 160 (c) 1600
  32. 32.Best estimate of 500 + 656? (a) 1400 (b) 1000 (c) 1200
  33. 33.Best estimate of 797 + 743? (a) 1500 (b) 1700 (c) 1300
  34. 34.Best estimate of 44 × 18? (a) 80 (b) 800 (c) 8000
  35. 35.Best estimate of 727 + 654? (a) 1400 (b) 1200 (c) 1600
  36. 36.Best estimate of 28 × 80? (a) 240 (b) 2400 (c) 24000
  37. 37.Best estimate of 542 + 125? (a) 600 (b) 400 (c) 800
  38. 38.Best estimate of 92 × 24? (a) 18000 (b) 180 (c) 1800
  39. 39.Best estimate of 29 × 44? (a) 120 (b) 1200 (c) 12000
  40. 40.Best estimate of 351 + 683? (a) 1300 (b) 900 (c) 1100

Answer key

  1. 700
  2. 2100
  3. 2400
  4. 900
  5. 1600
  6. 1500
  7. 4200
  8. 4000
  9. 800
  10. 600
  11. 1500
  12. 5000
  13. 3600
  14. 3600
  15. 2400
  16. 600
  17. 1400
  18. 9000
  19. 800
  20. 700
  21. 4900
  22. 800
  23. 1300
  24. 900
  25. 600
  26. 700
  27. 1200
  28. 1600
  29. 1000
  30. 1600
  31. 1600
  32. 1200
  33. 1500
  34. 800
  35. 1400
  36. 2400
  37. 600
  38. 1800
  39. 1200
  40. 1100

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