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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 960 · 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 413 + 206? (a) 400 (b) 800 (c) 600
  2. 2.Best estimate of 713 + 380? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 454 + 249? (a) 500 (b) 900 (c) 700
  4. 4.Best estimate of 160 + 791? (a) 1200 (b) 800 (c) 1000
  5. 5.Best estimate of 98 × 78? (a) 80000 (b) 8000 (c) 800
  6. 6.Best estimate of 78 × 48? (a) 40000 (b) 4000 (c) 400
  7. 7.Best estimate of 59 × 86? (a) 540 (b) 5400 (c) 54000
  8. 8.Best estimate of 529 + 268? (a) 800 (b) 600 (c) 1000
  9. 9.Best estimate of 88 × 16? (a) 180 (b) 1800 (c) 18000
  10. 10.Best estimate of 27 × 37? (a) 12000 (b) 120 (c) 1200
  11. 11.Best estimate of 180 + 310? (a) 700 (b) 500 (c) 300
  12. 12.Best estimate of 522 + 137? (a) 600 (b) 800 (c) 400
  13. 13.Best estimate of 51 × 38? (a) 200 (b) 20000 (c) 2000
  14. 14.Best estimate of 628 + 329? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 43 × 48? (a) 2000 (b) 20000 (c) 200
  16. 16.Best estimate of 72 × 18? (a) 140 (b) 14000 (c) 1400
  17. 17.Best estimate of 704 + 474? (a) 1000 (b) 1200 (c) 1400
  18. 18.Best estimate of 735 + 715? (a) 1200 (b) 1400 (c) 1600
  19. 19.Best estimate of 274 + 468? (a) 1000 (b) 600 (c) 800
  20. 20.Best estimate of 454 + 247? (a) 700 (b) 900 (c) 500
  21. 21.Best estimate of 84 × 23? (a) 160 (b) 16000 (c) 1600
  22. 22.Best estimate of 674 + 619? (a) 1300 (b) 1100 (c) 1500
  23. 23.Best estimate of 465 + 244? (a) 500 (b) 700 (c) 900
  24. 24.Best estimate of 273 + 581? (a) 900 (b) 1100 (c) 700
  25. 25.Best estimate of 57 × 78? (a) 4800 (b) 48000 (c) 480
  26. 26.Best estimate of 719 + 241? (a) 900 (b) 700 (c) 1100
  27. 27.Best estimate of 36 × 26? (a) 1200 (b) 120 (c) 12000
  28. 28.Best estimate of 56 × 52? (a) 300 (b) 3000 (c) 30000
  29. 29.Best estimate of 369 + 666? (a) 900 (b) 1100 (c) 1300
  30. 30.Best estimate of 86 × 54? (a) 45000 (b) 450 (c) 4500
  31. 31.Best estimate of 842 + 392? (a) 1200 (b) 1400 (c) 1000
  32. 32.Best estimate of 174 + 445? (a) 400 (b) 600 (c) 800
  33. 33.Best estimate of 711 + 230? (a) 700 (b) 1100 (c) 900
  34. 34.Best estimate of 689 + 195? (a) 1100 (b) 700 (c) 900
  35. 35.Best estimate of 77 × 49? (a) 4000 (b) 40000 (c) 400
  36. 36.Best estimate of 23 × 96? (a) 2000 (b) 20000 (c) 200
  37. 37.Best estimate of 649 + 713? (a) 1100 (b) 1500 (c) 1300
  38. 38.Best estimate of 351 + 861? (a) 1100 (b) 1300 (c) 1500
  39. 39.Best estimate of 809 + 615? (a) 1400 (b) 1200 (c) 1600
  40. 40.Best estimate of 81 × 81? (a) 6400 (b) 64000 (c) 640

Answer key

  1. 600
  2. 1100
  3. 700
  4. 1000
  5. 8000
  6. 4000
  7. 5400
  8. 800
  9. 1800
  10. 1200
  11. 500
  12. 600
  13. 2000
  14. 900
  15. 2000
  16. 1400
  17. 1200
  18. 1400
  19. 800
  20. 700
  21. 1600
  22. 1300
  23. 700
  24. 900
  25. 4800
  26. 900
  27. 1200
  28. 3000
  29. 1100
  30. 4500
  31. 1200
  32. 600
  33. 900
  34. 900
  35. 4000
  36. 2000
  37. 1300
  38. 1300
  39. 1400
  40. 6400

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