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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 344 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 5036 ÷ 59? (a) 84 (b) 8400 (c) 840
  2. 2.Best estimate of 3146 ÷ 37? (a) 79 (b) 7900 (c) 790
  3. 3.Best estimate of 3232 ÷ 37? (a) 8100 (b) 810 (c) 81
  4. 4.Best estimate of 3782 ÷ 66? (a) 5400 (b) 54 (c) 540
  5. 5.√79 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 9.2
  6. 6.Best estimate of 3022 ÷ 86? (a) 340 (b) 34 (c) 3400
  7. 7.√37 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.1 (d) 6.2
  8. 8.Best estimate of 884 ÷ 26? (a) 290 (b) 2900 (c) 29
  9. 9.√82 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.2 (d) 9.1
  10. 10.Best estimate of 6792 ÷ 79? (a) 850 (b) 8500 (c) 85
  11. 11.Best estimate of 2381 ÷ 32? (a) 7900 (b) 790 (c) 79
  12. 12.Best estimate of 3156 ÷ 44? (a) 790 (b) 79 (c) 7900
  13. 13.√90 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6
  14. 14.Best estimate of 845 ÷ 53? (a) 170 (b) 17 (c) 1700
  15. 15.Best estimate of 1752 ÷ 86? (a) 19 (b) 1900 (c) 190
  16. 16.Best estimate of 4220 ÷ 77? (a) 530 (b) 53 (c) 5300
  17. 17.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.2 (d) 7.5
  18. 18.Best estimate of 1118 ÷ 84? (a) 140 (b) 1400 (c) 14
  19. 19.Best estimate of 1803 ÷ 28? (a) 60 (b) 6000 (c) 600
  20. 20.√41 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.4
  21. 21.Best estimate of 3151 ÷ 37? (a) 790 (b) 79 (c) 7900
  22. 22.Best estimate of 1372 ÷ 24? (a) 690 (b) 69 (c) 6900
  23. 23.Best estimate of 1752 ÷ 22? (a) 88 (b) 880 (c) 8800
  24. 24.√21 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.6 (d) 4.7
  25. 25.Best estimate of 1414 ÷ 32? (a) 47 (b) 4700 (c) 470
  26. 26.√40 to 1 decimal place? (a) 6.2 (b) 6.5 (c) 6.4 (d) 6.3
  27. 27.√46 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.9 (d) 6.8
  28. 28.√74 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.6 (d) 8.8
  29. 29.Best estimate of 5448 ÷ 63? (a) 9100 (b) 910 (c) 91
  30. 30.Best estimate of 2823 ÷ 76? (a) 3500 (b) 350 (c) 35
  31. 31.√20 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.5 (d) 4.3
  32. 32.√29 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.4 (d) 5.2
  33. 33.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.3
  34. 34.√92 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.7
  35. 35.Best estimate of 4326 ÷ 54? (a) 87 (b) 870 (c) 8700
  36. 36.√85 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4
  37. 37.Best estimate of 807 ÷ 41? (a) 2000 (b) 200 (c) 20
  38. 38.√26 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 5.0 (d) 4.9
  39. 39.√88 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.4 (d) 9.3
  40. 40.√66 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 8.1

Answer key

  1. 84
  2. 79
  3. 81
  4. 54
  5. 8.9
  6. 34
  7. 6.1
  8. 29
  9. 9.1
  10. 85
  11. 79
  12. 79
  13. 9.5
  14. 17
  15. 19
  16. 53
  17. 7.3
  18. 14
  19. 60
  20. 6.4
  21. 79
  22. 69
  23. 88
  24. 4.6
  25. 47
  26. 6.3
  27. 6.8
  28. 8.6
  29. 91
  30. 35
  31. 4.5
  32. 5.4
  33. 7.6
  34. 9.6
  35. 87
  36. 9.2
  37. 20
  38. 5.1
  39. 9.4
  40. 8.1

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