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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 76 · 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 271 + 815? (a) 900 (b) 1100 (c) 1300
  2. 2.Best estimate of 128 + 726? (a) 600 (b) 1000 (c) 800
  3. 3.Best estimate of 89 × 20? (a) 180 (b) 18000 (c) 1800
  4. 4.Best estimate of 96 × 24? (a) 200 (b) 20000 (c) 2000
  5. 5.Best estimate of 22 × 26? (a) 6000 (b) 60 (c) 600
  6. 6.Best estimate of 88 × 96? (a) 900 (b) 90000 (c) 9000
  7. 7.Best estimate of 96 × 69? (a) 7000 (b) 70000 (c) 700
  8. 8.Best estimate of 407 + 808? (a) 1000 (b) 1400 (c) 1200
  9. 9.Best estimate of 39 × 90? (a) 3600 (b) 360 (c) 36000
  10. 10.Best estimate of 575 + 547? (a) 1300 (b) 1100 (c) 900
  11. 11.Best estimate of 736 + 743? (a) 1600 (b) 1200 (c) 1400
  12. 12.Best estimate of 31 × 52? (a) 150 (b) 15000 (c) 1500
  13. 13.Best estimate of 286 + 341? (a) 800 (b) 400 (c) 600
  14. 14.Best estimate of 856 + 373? (a) 1500 (b) 1100 (c) 1300
  15. 15.Best estimate of 29 × 14? (a) 3000 (b) 300 (c) 30
  16. 16.Best estimate of 98 × 57? (a) 6000 (b) 600 (c) 60000
  17. 17.Best estimate of 299 + 333? (a) 600 (b) 800 (c) 400
  18. 18.Best estimate of 499 + 224? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 82 × 33? (a) 2400 (b) 24000 (c) 240
  20. 20.Best estimate of 391 + 720? (a) 1100 (b) 900 (c) 1300
  21. 21.Best estimate of 53 × 59? (a) 3000 (b) 30000 (c) 300
  22. 22.Best estimate of 97 × 29? (a) 30000 (b) 3000 (c) 300
  23. 23.Best estimate of 43 × 31? (a) 12000 (b) 1200 (c) 120
  24. 24.Best estimate of 197 + 338? (a) 500 (b) 300 (c) 700
  25. 25.Best estimate of 369 + 390? (a) 1000 (b) 600 (c) 800
  26. 26.Best estimate of 26 × 58? (a) 18000 (b) 180 (c) 1800
  27. 27.Best estimate of 196 + 486? (a) 900 (b) 700 (c) 500
  28. 28.Best estimate of 96 × 17? (a) 2000 (b) 200 (c) 20000
  29. 29.Best estimate of 28 × 46? (a) 1500 (b) 150 (c) 15000
  30. 30.Best estimate of 36 × 30? (a) 12000 (b) 120 (c) 1200
  31. 31.Best estimate of 851 + 438? (a) 1500 (b) 1300 (c) 1100
  32. 32.Best estimate of 351 + 224? (a) 600 (b) 400 (c) 800
  33. 33.Best estimate of 745 + 661? (a) 1200 (b) 1400 (c) 1600
  34. 34.Best estimate of 205 + 492? (a) 700 (b) 500 (c) 900
  35. 35.Best estimate of 444 + 736? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 307 + 294? (a) 600 (b) 400 (c) 800
  37. 37.Best estimate of 731 + 864? (a) 1800 (b) 1400 (c) 1600
  38. 38.Best estimate of 96 × 70? (a) 7000 (b) 70000 (c) 700
  39. 39.Best estimate of 312 + 180? (a) 500 (b) 700 (c) 300
  40. 40.Best estimate of 685 + 254? (a) 1000 (b) 1200 (c) 800

Answer key

  1. 1100
  2. 800
  3. 1800
  4. 2000
  5. 600
  6. 9000
  7. 7000
  8. 1200
  9. 3600
  10. 1100
  11. 1400
  12. 1500
  13. 600
  14. 1300
  15. 300
  16. 6000
  17. 600
  18. 700
  19. 2400
  20. 1100
  21. 3000
  22. 3000
  23. 1200
  24. 500
  25. 800
  26. 1800
  27. 700
  28. 2000
  29. 1500
  30. 1200
  31. 1300
  32. 600
  33. 1400
  34. 700
  35. 1100
  36. 600
  37. 1600
  38. 7000
  39. 500
  40. 1000

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