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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 99 · 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 51 × 38? (a) 200 (b) 20000 (c) 2000
  2. 2.Best estimate of 26 × 76? (a) 240 (b) 24000 (c) 2400
  3. 3.Best estimate of 51 × 68? (a) 35000 (b) 350 (c) 3500
  4. 4.Best estimate of 343 + 417? (a) 900 (b) 700 (c) 500
  5. 5.Best estimate of 18 × 52? (a) 100 (b) 1000 (c) 10000
  6. 6.Best estimate of 390 + 438? (a) 800 (b) 600 (c) 1000
  7. 7.Best estimate of 799 + 387? (a) 1400 (b) 1200 (c) 1000
  8. 8.Best estimate of 24 × 70? (a) 1400 (b) 14000 (c) 140
  9. 9.Best estimate of 340 + 123? (a) 600 (b) 400 (c) 200
  10. 10.Best estimate of 194 + 548? (a) 700 (b) 500 (c) 900
  11. 11.Best estimate of 41 × 66? (a) 28000 (b) 280 (c) 2800
  12. 12.Best estimate of 589 + 869? (a) 1300 (b) 1500 (c) 1700
  13. 13.Best estimate of 151 + 670? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 57 × 76? (a) 480 (b) 48000 (c) 4800
  15. 15.Best estimate of 49 × 26? (a) 15000 (b) 1500 (c) 150
  16. 16.Best estimate of 697 + 254? (a) 1000 (b) 800 (c) 1200
  17. 17.Best estimate of 161 + 578? (a) 1000 (b) 800 (c) 600
  18. 18.Best estimate of 37 × 96? (a) 400 (b) 40000 (c) 4000
  19. 19.Best estimate of 797 + 121? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 73 × 17? (a) 140 (b) 14000 (c) 1400
  21. 21.Best estimate of 307 + 793? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 57 × 89? (a) 540 (b) 54000 (c) 5400
  23. 23.Best estimate of 312 + 682? (a) 1200 (b) 1000 (c) 800
  24. 24.Best estimate of 33 × 31? (a) 9000 (b) 900 (c) 90
  25. 25.Best estimate of 139 + 352? (a) 700 (b) 300 (c) 500
  26. 26.Best estimate of 471 + 335? (a) 1000 (b) 800 (c) 600
  27. 27.Best estimate of 708 + 583? (a) 1100 (b) 1500 (c) 1300
  28. 28.Best estimate of 211 + 485? (a) 900 (b) 500 (c) 700
  29. 29.Best estimate of 91 × 56? (a) 540 (b) 5400 (c) 54000
  30. 30.Best estimate of 338 + 408? (a) 900 (b) 500 (c) 700
  31. 31.Best estimate of 37 × 66? (a) 2800 (b) 280 (c) 28000
  32. 32.Best estimate of 93 × 56? (a) 540 (b) 5400 (c) 54000
  33. 33.Best estimate of 687 + 786? (a) 1300 (b) 1700 (c) 1500
  34. 34.Best estimate of 391 + 825? (a) 1200 (b) 1000 (c) 1400
  35. 35.Best estimate of 54 × 13? (a) 5000 (b) 500 (c) 50
  36. 36.Best estimate of 50 × 32? (a) 150 (b) 15000 (c) 1500
  37. 37.Best estimate of 29 × 50? (a) 1500 (b) 150 (c) 15000
  38. 38.Best estimate of 138 + 624? (a) 700 (b) 900 (c) 500
  39. 39.Best estimate of 557 + 315? (a) 700 (b) 900 (c) 1100
  40. 40.Best estimate of 385 + 749? (a) 1300 (b) 900 (c) 1100

Answer key

  1. 2000
  2. 2400
  3. 3500
  4. 700
  5. 1000
  6. 800
  7. 1200
  8. 1400
  9. 400
  10. 700
  11. 2800
  12. 1500
  13. 900
  14. 4800
  15. 1500
  16. 1000
  17. 800
  18. 4000
  19. 900
  20. 1400
  21. 1100
  22. 5400
  23. 1000
  24. 900
  25. 500
  26. 800
  27. 1300
  28. 700
  29. 5400
  30. 700
  31. 2800
  32. 5400
  33. 1500
  34. 1200
  35. 500
  36. 1500
  37. 1500
  38. 700
  39. 900
  40. 1100

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