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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 816 · 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 4041 ÷ 52? (a) 8100 (b) 810 (c) 81
  2. 2.Best estimate of 5771 ÷ 67? (a) 820 (b) 8200 (c) 82
  3. 3.√83 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 9.3
  4. 4.√44 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.8
  5. 5.Best estimate of 1845 ÷ 26? (a) 62 (b) 620 (c) 6200
  6. 6.Best estimate of 1660 ÷ 32? (a) 5500 (b) 55 (c) 550
  7. 7.Best estimate of 728 ÷ 32? (a) 2400 (b) 240 (c) 24
  8. 8.Best estimate of 1538 ÷ 49? (a) 31 (b) 3100 (c) 310
  9. 9.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 6.9
  10. 10.√43 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.9 (d) 6.6
  11. 11.√59 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.7 (d) 7.8
  12. 12.Best estimate of 3293 ÷ 57? (a) 55 (b) 550 (c) 5500
  13. 13.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 9.8 (d) 10.0
  14. 14.Best estimate of 1336 ÷ 66? (a) 1900 (b) 19 (c) 190
  15. 15.Best estimate of 1997 ÷ 64? (a) 33 (b) 3300 (c) 330
  16. 16.√67 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  17. 17.√80 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.0 (d) 9.1
  18. 18.√23 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.8 (d) 4.7
  19. 19.Best estimate of 543 ÷ 32? (a) 180 (b) 1800 (c) 18
  20. 20.Best estimate of 4640 ÷ 83? (a) 580 (b) 58 (c) 5800
  21. 21.√69 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.3 (d) 8.4
  22. 22.√38 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.3 (d) 6.4
  23. 23.Best estimate of 740 ÷ 36? (a) 19 (b) 190 (c) 1900
  24. 24.√87 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.6
  25. 25.Best estimate of 4486 ÷ 53? (a) 900 (b) 9000 (c) 90
  26. 26.√71 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.4
  27. 27.√66 to 1 decimal place? (a) 7.9 (b) 8.2 (c) 8.0 (d) 8.1
  28. 28.Best estimate of 6728 ÷ 86? (a) 75 (b) 7500 (c) 750
  29. 29.Best estimate of 2579 ÷ 28? (a) 860 (b) 8600 (c) 86
  30. 30.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.7
  31. 31.√61 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 7.8 (d) 8.0
  32. 32.Best estimate of 1833 ÷ 42? (a) 46 (b) 460 (c) 4600
  33. 33.Best estimate of 1315 ÷ 67? (a) 190 (b) 19 (c) 1900
  34. 34.√90 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.5 (d) 9.3
  35. 35.√56 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.8
  36. 36.√29 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.5 (d) 5.7
  37. 37.Best estimate of 2017 ÷ 41? (a) 500 (b) 5000 (c) 50
  38. 38.Best estimate of 2847 ÷ 36? (a) 7100 (b) 710 (c) 71
  39. 39.Best estimate of 5185 ÷ 66? (a) 7400 (b) 74 (c) 740
  40. 40.Best estimate of 5821 ÷ 66? (a) 830 (b) 8300 (c) 83

Answer key

  1. 81
  2. 82
  3. 9.1
  4. 6.6
  5. 62
  6. 55
  7. 24
  8. 31
  9. 7.1
  10. 6.6
  11. 7.7
  12. 55
  13. 9.9
  14. 19
  15. 33
  16. 8.2
  17. 8.9
  18. 4.8
  19. 18
  20. 58
  21. 8.3
  22. 6.2
  23. 19
  24. 9.3
  25. 90
  26. 8.4
  27. 8.1
  28. 75
  29. 86
  30. 7.4
  31. 7.8
  32. 46
  33. 19
  34. 9.5
  35. 7.5
  36. 5.4
  37. 50
  38. 71
  39. 74
  40. 83

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