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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 183 · 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.√82 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  2. 2.√24 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.9 (d) 4.8
  3. 3.Best estimate of 1558 ÷ 22? (a) 78 (b) 7800 (c) 780
  4. 4.√50 to 1 decimal place? (a) 7.0 (b) 7.3 (c) 7.1 (d) 7.2
  5. 5.Best estimate of 5729 ÷ 82? (a) 72 (b) 720 (c) 7200
  6. 6.Best estimate of 4694 ÷ 52? (a) 94 (b) 940 (c) 9400
  7. 7.Best estimate of 3047 ÷ 32? (a) 1020 (b) 102 (c) 10200
  8. 8.Best estimate of 5458 ÷ 64? (a) 910 (b) 9100 (c) 91
  9. 9.Best estimate of 2991 ÷ 36? (a) 75 (b) 750 (c) 7500
  10. 10.Best estimate of 5325 ÷ 81? (a) 6700 (b) 67 (c) 670
  11. 11.√56 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  12. 12.√37 to 1 decimal place? (a) 6.1 (b) 5.8 (c) 5.9 (d) 6.0
  13. 13.√98 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.8 (d) 9.7
  14. 14.√59 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.9 (d) 7.7
  15. 15.√78 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.5 (d) 8.6
  16. 16.Best estimate of 6284 ÷ 82? (a) 790 (b) 7900 (c) 79
  17. 17.Best estimate of 4626 ÷ 52? (a) 930 (b) 9300 (c) 93
  18. 18.Best estimate of 699 ÷ 37? (a) 1700 (b) 17 (c) 170
  19. 19.√86 to 1 decimal place? (a) 9.3 (b) 9.0 (c) 9.2 (d) 9.1
  20. 20.√61 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.8 (d) 7.7
  21. 21.√55 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.4
  22. 22.√92 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 9.6
  23. 23.√80 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.9
  24. 24.Best estimate of 1227 ÷ 22? (a) 6100 (b) 610 (c) 61
  25. 25.√29 to 1 decimal place? (a) 5.2 (b) 5.5 (c) 5.4 (d) 5.3
  26. 26.Best estimate of 3107 ÷ 66? (a) 4400 (b) 440 (c) 44
  27. 27.√47 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.9 (d) 6.8
  28. 28.Best estimate of 3220 ÷ 76? (a) 400 (b) 40 (c) 4000
  29. 29.Best estimate of 3644 ÷ 42? (a) 91 (b) 910 (c) 9100
  30. 30.Best estimate of 4901 ÷ 52? (a) 9800 (b) 98 (c) 980
  31. 31.Best estimate of 789 ÷ 36? (a) 200 (b) 2000 (c) 20
  32. 32.Best estimate of 2690 ÷ 83? (a) 3400 (b) 340 (c) 34
  33. 33.Best estimate of 787 ÷ 32? (a) 2600 (b) 26 (c) 260
  34. 34.√66 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.3 (d) 8.1
  35. 35.Best estimate of 2201 ÷ 62? (a) 370 (b) 3700 (c) 37
  36. 36.Best estimate of 3759 ÷ 43? (a) 940 (b) 9400 (c) 94
  37. 37.Best estimate of 4985 ÷ 64? (a) 830 (b) 8300 (c) 83
  38. 38.Best estimate of 3694 ÷ 41? (a) 9200 (b) 92 (c) 920
  39. 39.Best estimate of 3458 ÷ 59? (a) 580 (b) 5800 (c) 58
  40. 40.Best estimate of 1144 ÷ 51? (a) 230 (b) 23 (c) 2300

Answer key

  1. 9.1
  2. 4.9
  3. 78
  4. 7.1
  5. 72
  6. 94
  7. 102
  8. 91
  9. 75
  10. 67
  11. 7.5
  12. 6.1
  13. 9.9
  14. 7.7
  15. 8.8
  16. 79
  17. 93
  18. 17
  19. 9.3
  20. 7.8
  21. 7.4
  22. 9.6
  23. 8.9
  24. 61
  25. 5.4
  26. 44
  27. 6.9
  28. 40
  29. 91
  30. 98
  31. 20
  32. 34
  33. 26
  34. 8.1
  35. 37
  36. 94
  37. 83
  38. 92
  39. 58
  40. 23

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