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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 182 · 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.√90 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.5
  2. 2.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  3. 3.Best estimate of 546 ÷ 24? (a) 270 (b) 2700 (c) 27
  4. 4.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.9 (d) 9.8
  5. 5.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.4 (d) 9.5
  6. 6.Best estimate of 2529 ÷ 36? (a) 630 (b) 6300 (c) 63
  7. 7.Best estimate of 1602 ÷ 29? (a) 530 (b) 5300 (c) 53
  8. 8.√82 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 9.1
  9. 9.Best estimate of 764 ÷ 27? (a) 250 (b) 25 (c) 2500
  10. 10.√74 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.8
  11. 11.Best estimate of 3488 ÷ 39? (a) 8700 (b) 87 (c) 870
  12. 12.Best estimate of 2102 ÷ 37? (a) 5300 (b) 53 (c) 530
  13. 13.√46 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.5
  14. 14.Best estimate of 4448 ÷ 56? (a) 7400 (b) 740 (c) 74
  15. 15.Best estimate of 2150 ÷ 29? (a) 7200 (b) 72 (c) 720
  16. 16.Best estimate of 3307 ÷ 43? (a) 83 (b) 830 (c) 8300
  17. 17.Best estimate of 1031 ÷ 37? (a) 26 (b) 2600 (c) 260
  18. 18.Best estimate of 3096 ÷ 52? (a) 62 (b) 620 (c) 6200
  19. 19.Best estimate of 1371 ÷ 38? (a) 3400 (b) 340 (c) 34
  20. 20.Best estimate of 1841 ÷ 29? (a) 61 (b) 610 (c) 6100
  21. 21.Best estimate of 1732 ÷ 21? (a) 87 (b) 870 (c) 8700
  22. 22.√38 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 5.9
  23. 23.Best estimate of 2087 ÷ 62? (a) 35 (b) 350 (c) 3500
  24. 24.Best estimate of 925 ÷ 62? (a) 1500 (b) 15 (c) 150
  25. 25.√29 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.4 (d) 5.2
  26. 26.Best estimate of 2910 ÷ 86? (a) 320 (b) 3200 (c) 32
  27. 27.√84 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.5
  28. 28.Best estimate of 5572 ÷ 82? (a) 700 (b) 70 (c) 7000
  29. 29.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  30. 30.Best estimate of 5861 ÷ 77? (a) 730 (b) 7300 (c) 73
  31. 31.√47 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.9
  32. 32.Best estimate of 1787 ÷ 26? (a) 600 (b) 6000 (c) 60
  33. 33.√55 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2
  34. 34.Best estimate of 4525 ÷ 57? (a) 75 (b) 7500 (c) 750
  35. 35.Best estimate of 2819 ÷ 62? (a) 470 (b) 4700 (c) 47
  36. 36.Best estimate of 1168 ÷ 82? (a) 150 (b) 15 (c) 1500
  37. 37.√35 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.9
  38. 38.Best estimate of 925 ÷ 23? (a) 4600 (b) 460 (c) 46
  39. 39.Best estimate of 3787 ÷ 48? (a) 760 (b) 7600 (c) 76
  40. 40.√77 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.8 (d) 8.6

Answer key

  1. 9.5
  2. 8.2
  3. 27
  4. 9.6
  5. 9.7
  6. 63
  7. 53
  8. 9.1
  9. 25
  10. 8.6
  11. 87
  12. 53
  13. 6.8
  14. 74
  15. 72
  16. 83
  17. 26
  18. 62
  19. 34
  20. 61
  21. 87
  22. 6.2
  23. 35
  24. 15
  25. 5.4
  26. 32
  27. 9.2
  28. 70
  29. 8.1
  30. 73
  31. 6.9
  32. 60
  33. 7.4
  34. 75
  35. 47
  36. 15
  37. 5.9
  38. 46
  39. 76
  40. 8.8

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