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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 475 · 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 3882 ÷ 87? (a) 430 (b) 43 (c) 4300
  2. 2.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 5.9
  3. 3.Best estimate of 641 ÷ 36? (a) 16 (b) 1600 (c) 160
  4. 4.Best estimate of 4432 ÷ 58? (a) 7400 (b) 74 (c) 740
  5. 5.√27 to 1 decimal place? (a) 5.3 (b) 5.0 (c) 5.1 (d) 5.2
  6. 6.Best estimate of 4393 ÷ 68? (a) 6300 (b) 630 (c) 63
  7. 7.√26 to 1 decimal place? (a) 5.2 (b) 4.9 (c) 5.1 (d) 5.0
  8. 8.√85 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 9.2
  9. 9.Best estimate of 1226 ÷ 33? (a) 41 (b) 4100 (c) 410
  10. 10.Best estimate of 594 ÷ 32? (a) 200 (b) 2000 (c) 20
  11. 11.√41 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.1 (d) 6.3
  12. 12.√47 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  13. 13.√22 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.6 (d) 4.7
  14. 14.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.3
  15. 15.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.4
  16. 16.Best estimate of 3327 ÷ 41? (a) 83 (b) 8300 (c) 830
  17. 17.Best estimate of 2370 ÷ 39? (a) 5900 (b) 59 (c) 590
  18. 18.Best estimate of 2574 ÷ 36? (a) 6400 (b) 640 (c) 64
  19. 19.√29 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.6 (d) 5.5
  20. 20.√34 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.8 (d) 5.9
  21. 21.√66 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  22. 22.Best estimate of 760 ÷ 36? (a) 1900 (b) 19 (c) 190
  23. 23.√53 to 1 decimal place? (a) 7.0 (b) 7.3 (c) 7.2 (d) 7.1
  24. 24.Best estimate of 6798 ÷ 84? (a) 8500 (b) 85 (c) 850
  25. 25.√44 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.4
  26. 26.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.5
  27. 27.√98 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.9
  28. 28.Best estimate of 2809 ÷ 38? (a) 70 (b) 700 (c) 7000
  29. 29.Best estimate of 950 ÷ 67? (a) 1400 (b) 140 (c) 14
  30. 30.Best estimate of 6985 ÷ 82? (a) 870 (b) 87 (c) 8700
  31. 31.Best estimate of 2422 ÷ 26? (a) 81 (b) 8100 (c) 810
  32. 32.Best estimate of 1640 ÷ 54? (a) 33 (b) 3300 (c) 330
  33. 33.Best estimate of 1881 ÷ 21? (a) 940 (b) 9400 (c) 94
  34. 34.Best estimate of 1118 ÷ 21? (a) 560 (b) 5600 (c) 56
  35. 35.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  36. 36.√86 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  37. 37.Best estimate of 2341 ÷ 86? (a) 26 (b) 2600 (c) 260
  38. 38.Best estimate of 3492 ÷ 81? (a) 4400 (b) 440 (c) 44
  39. 39.√61 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.8 (d) 7.9
  40. 40.Best estimate of 711 ÷ 32? (a) 24 (b) 2400 (c) 240

Answer key

  1. 43
  2. 6.1
  3. 16
  4. 74
  5. 5.2
  6. 63
  7. 5.1
  8. 9.2
  9. 41
  10. 20
  11. 6.4
  12. 6.9
  13. 4.7
  14. 7.4
  15. 8.6
  16. 83
  17. 59
  18. 64
  19. 5.4
  20. 5.8
  21. 8.1
  22. 19
  23. 7.3
  24. 85
  25. 6.6
  26. 8.2
  27. 9.9
  28. 70
  29. 14
  30. 87
  31. 81
  32. 33
  33. 94
  34. 56
  35. 4.8
  36. 9.3
  37. 26
  38. 44
  39. 7.8
  40. 24

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