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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 256 · 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 3214 ÷ 89? (a) 3600 (b) 36 (c) 360
  2. 2.Best estimate of 2270 ÷ 28? (a) 7600 (b) 760 (c) 76
  3. 3.Best estimate of 3369 ÷ 81? (a) 420 (b) 4200 (c) 42
  4. 4.Best estimate of 795 ÷ 21? (a) 400 (b) 40 (c) 4000
  5. 5.Best estimate of 2366 ÷ 73? (a) 3400 (b) 34 (c) 340
  6. 6.√50 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.0 (d) 7.1
  7. 7.√90 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.5 (d) 9.4
  8. 8.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.1 (d) 10.0
  9. 9.√77 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  10. 10.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  11. 11.√37 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.1 (d) 6.2
  12. 12.Best estimate of 4264 ÷ 62? (a) 710 (b) 7100 (c) 71
  13. 13.√29 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.3
  14. 14.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.9 (d) 8.2
  15. 15.Best estimate of 1357 ÷ 59? (a) 2300 (b) 23 (c) 230
  16. 16.Best estimate of 2608 ÷ 32? (a) 8700 (b) 87 (c) 870
  17. 17.√26 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.4 (d) 5.1
  18. 18.Best estimate of 7474 ÷ 83? (a) 93 (b) 930 (c) 9300
  19. 19.Best estimate of 473 ÷ 32? (a) 160 (b) 16 (c) 1600
  20. 20.Best estimate of 5115 ÷ 62? (a) 850 (b) 8500 (c) 85
  21. 21.√87 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.5 (d) 9.4
  22. 22.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 8.0
  23. 23.√55 to 1 decimal place? (a) 7.2 (b) 7.5 (c) 7.4 (d) 7.3
  24. 24.√75 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  25. 25.Best estimate of 2149 ÷ 41? (a) 54 (b) 540 (c) 5400
  26. 26.√65 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 8.2
  27. 27.Best estimate of 3949 ÷ 49? (a) 7900 (b) 79 (c) 790
  28. 28.Best estimate of 2931 ÷ 36? (a) 73 (b) 7300 (c) 730
  29. 29.√23 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.5
  30. 30.√32 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.7 (d) 5.5
  31. 31.Best estimate of 823 ÷ 28? (a) 27 (b) 2700 (c) 270
  32. 32.√51 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.9 (d) 7.1
  33. 33.Best estimate of 810 ÷ 37? (a) 20 (b) 200 (c) 2000
  34. 34.Best estimate of 2292 ÷ 49? (a) 4600 (b) 460 (c) 46
  35. 35.Best estimate of 2179 ÷ 82? (a) 27 (b) 270 (c) 2700
  36. 36.√86 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.6 (d) 9.4
  37. 37.Best estimate of 2545 ÷ 28? (a) 85 (b) 850 (c) 8500
  38. 38.Best estimate of 2414 ÷ 64? (a) 4000 (b) 400 (c) 40
  39. 39.Best estimate of 5248 ÷ 78? (a) 66 (b) 660 (c) 6600
  40. 40.Best estimate of 1420 ÷ 21? (a) 7100 (b) 710 (c) 71

Answer key

  1. 36
  2. 76
  3. 42
  4. 40
  5. 34
  6. 7.1
  7. 9.5
  8. 9.9
  9. 8.8
  10. 5.8
  11. 6.1
  12. 71
  13. 5.4
  14. 8.1
  15. 23
  16. 87
  17. 5.1
  18. 93
  19. 16
  20. 85
  21. 9.3
  22. 7.8
  23. 7.4
  24. 8.7
  25. 54
  26. 8.1
  27. 79
  28. 73
  29. 4.8
  30. 5.7
  31. 27
  32. 7.1
  33. 20
  34. 46
  35. 27
  36. 9.3
  37. 85
  38. 40
  39. 66
  40. 71

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