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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 454 · 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 247 + 793? (a) 1000 (b) 1200 (c) 800
  2. 2.Best estimate of 50 × 24? (a) 10000 (b) 100 (c) 1000
  3. 3.Best estimate of 66 × 53? (a) 35000 (b) 3500 (c) 350
  4. 4.Best estimate of 283 + 402? (a) 900 (b) 500 (c) 700
  5. 5.Best estimate of 394 + 290? (a) 900 (b) 500 (c) 700
  6. 6.Best estimate of 540 + 124? (a) 400 (b) 600 (c) 800
  7. 7.Best estimate of 806 + 724? (a) 1500 (b) 1700 (c) 1300
  8. 8.Best estimate of 51 × 36? (a) 20000 (b) 2000 (c) 200
  9. 9.Best estimate of 33 × 84? (a) 24000 (b) 240 (c) 2400
  10. 10.Best estimate of 86 × 46? (a) 4500 (b) 45000 (c) 450
  11. 11.Best estimate of 186 + 788? (a) 800 (b) 1000 (c) 1200
  12. 12.Best estimate of 18 × 17? (a) 40 (b) 400 (c) 4000
  13. 13.Best estimate of 91 × 73? (a) 630 (b) 6300 (c) 63000
  14. 14.Best estimate of 151 + 315? (a) 300 (b) 500 (c) 700
  15. 15.Best estimate of 28 × 91? (a) 270 (b) 2700 (c) 27000
  16. 16.Best estimate of 53 × 20? (a) 1000 (b) 100 (c) 10000
  17. 17.Best estimate of 519 + 344? (a) 800 (b) 600 (c) 1000
  18. 18.Best estimate of 46 × 98? (a) 500 (b) 5000 (c) 50000
  19. 19.Best estimate of 46 × 69? (a) 3500 (b) 35000 (c) 350
  20. 20.Best estimate of 791 + 312? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 149 + 228? (a) 100 (b) 300 (c) 500
  22. 22.Best estimate of 545 + 812? (a) 1100 (b) 1500 (c) 1300
  23. 23.Best estimate of 721 + 453? (a) 1200 (b) 1400 (c) 1000
  24. 24.Best estimate of 502 + 325? (a) 600 (b) 800 (c) 1000
  25. 25.Best estimate of 57 × 50? (a) 3000 (b) 30000 (c) 300
  26. 26.Best estimate of 73 × 20? (a) 1400 (b) 140 (c) 14000
  27. 27.Best estimate of 384 + 494? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 84 × 86? (a) 72000 (b) 720 (c) 7200
  29. 29.Best estimate of 165 + 527? (a) 900 (b) 700 (c) 500
  30. 30.Best estimate of 446 + 178? (a) 400 (b) 600 (c) 800
  31. 31.Best estimate of 68 × 16? (a) 1400 (b) 140 (c) 14000
  32. 32.Best estimate of 57 × 98? (a) 6000 (b) 600 (c) 60000
  33. 33.Best estimate of 24 × 19? (a) 40 (b) 4000 (c) 400
  34. 34.Best estimate of 729 + 159? (a) 1100 (b) 900 (c) 700
  35. 35.Best estimate of 26 × 16? (a) 600 (b) 60 (c) 6000
  36. 36.Best estimate of 832 + 816? (a) 1600 (b) 1400 (c) 1800
  37. 37.Best estimate of 384 + 727? (a) 1300 (b) 1100 (c) 900
  38. 38.Best estimate of 56 × 28? (a) 18000 (b) 1800 (c) 180
  39. 39.Best estimate of 20 × 36? (a) 8000 (b) 80 (c) 800
  40. 40.Best estimate of 645 + 776? (a) 1600 (b) 1400 (c) 1200

Answer key

  1. 1000
  2. 1000
  3. 3500
  4. 700
  5. 700
  6. 600
  7. 1500
  8. 2000
  9. 2400
  10. 4500
  11. 1000
  12. 400
  13. 6300
  14. 500
  15. 2700
  16. 1000
  17. 800
  18. 5000
  19. 3500
  20. 1100
  21. 300
  22. 1300
  23. 1200
  24. 800
  25. 3000
  26. 1400
  27. 900
  28. 7200
  29. 700
  30. 600
  31. 1400
  32. 6000
  33. 400
  34. 900
  35. 600
  36. 1600
  37. 1100
  38. 1800
  39. 800
  40. 1400

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