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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 586 · 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.√20 to 1 decimal place? (a) 4.4 (b) 4.3 (c) 4.5 (d) 4.2
  2. 2.√59 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.5
  3. 3.√58 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.5
  4. 4.Best estimate of 1720 ÷ 36? (a) 430 (b) 4300 (c) 43
  5. 5.√41 to 1 decimal place? (a) 6.1 (b) 6.4 (c) 6.3 (d) 6.2
  6. 6.Best estimate of 1594 ÷ 32? (a) 530 (b) 5300 (c) 53
  7. 7.√80 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.2 (d) 9.1
  8. 8.Best estimate of 5949 ÷ 71? (a) 850 (b) 8500 (c) 85
  9. 9.√90 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.5 (d) 9.7
  10. 10.Best estimate of 2332 ÷ 26? (a) 7800 (b) 780 (c) 78
  11. 11.Best estimate of 2465 ÷ 29? (a) 820 (b) 8200 (c) 82
  12. 12.Best estimate of 7446 ÷ 83? (a) 93 (b) 930 (c) 9300
  13. 13.Best estimate of 2244 ÷ 36? (a) 5600 (b) 56 (c) 560
  14. 14.Best estimate of 1691 ÷ 23? (a) 850 (b) 8500 (c) 85
  15. 15.Best estimate of 3178 ÷ 49? (a) 64 (b) 6400 (c) 640
  16. 16.√38 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.2 (d) 6.1
  17. 17.√71 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.6 (d) 8.5
  18. 18.Best estimate of 5723 ÷ 83? (a) 72 (b) 720 (c) 7200
  19. 19.√27 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.3 (d) 5.2
  20. 20.Best estimate of 5696 ÷ 63? (a) 950 (b) 95 (c) 9500
  21. 21.Best estimate of 6648 ÷ 77? (a) 830 (b) 8300 (c) 83
  22. 22.√55 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.4 (d) 7.1
  23. 23.√51 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 7.3
  24. 24.Best estimate of 3783 ÷ 77? (a) 470 (b) 47 (c) 4700
  25. 25.√61 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.7 (d) 7.6
  26. 26.√79 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  27. 27.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.8
  28. 28.Best estimate of 2861 ÷ 62? (a) 4800 (b) 480 (c) 48
  29. 29.Best estimate of 4811 ÷ 66? (a) 69 (b) 6900 (c) 690
  30. 30.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 10.2 (d) 9.9
  31. 31.Best estimate of 2138 ÷ 34? (a) 7100 (b) 710 (c) 71
  32. 32.Best estimate of 3291 ÷ 51? (a) 660 (b) 6600 (c) 66
  33. 33.√42 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.3 (d) 6.4
  34. 34.√40 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.1
  35. 35.Best estimate of 3406 ÷ 79? (a) 4300 (b) 43 (c) 430
  36. 36.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.9
  37. 37.Best estimate of 5910 ÷ 66? (a) 84 (b) 8400 (c) 840
  38. 38.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.6 (d) 9.4
  39. 39.√47 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 7.2
  40. 40.Best estimate of 2624 ÷ 66? (a) 37 (b) 3700 (c) 370

Answer key

  1. 4.5
  2. 7.7
  3. 7.6
  4. 43
  5. 6.4
  6. 53
  7. 8.9
  8. 85
  9. 9.5
  10. 78
  11. 82
  12. 93
  13. 56
  14. 85
  15. 64
  16. 6.2
  17. 8.4
  18. 72
  19. 5.2
  20. 95
  21. 83
  22. 7.4
  23. 7.1
  24. 47
  25. 7.8
  26. 8.9
  27. 9.7
  28. 48
  29. 69
  30. 9.9
  31. 71
  32. 66
  33. 6.5
  34. 6.3
  35. 43
  36. 8.6
  37. 84
  38. 9.3
  39. 6.9
  40. 37

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