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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 716 · 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 3855 ÷ 42? (a) 9600 (b) 960 (c) 96
  2. 2.Best estimate of 4083 ÷ 53? (a) 82 (b) 820 (c) 8200
  3. 3.√61 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.8 (d) 7.7
  4. 4.√20 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.3 (d) 4.4
  5. 5.Best estimate of 742 ÷ 36? (a) 190 (b) 1900 (c) 19
  6. 6.Best estimate of 4087 ÷ 63? (a) 68 (b) 6800 (c) 680
  7. 7.√94 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.6 (d) 9.5
  8. 8.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  9. 9.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.4 (d) 6.3
  10. 10.Best estimate of 1024 ÷ 76? (a) 130 (b) 1300 (c) 13
  11. 11.Best estimate of 6400 ÷ 87? (a) 7100 (b) 71 (c) 710
  12. 12.√22 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.5
  13. 13.Best estimate of 6080 ÷ 81? (a) 7600 (b) 760 (c) 76
  14. 14.√24 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.9
  15. 15.Best estimate of 918 ÷ 51? (a) 180 (b) 18 (c) 1800
  16. 16.Best estimate of 2105 ÷ 37? (a) 5300 (b) 530 (c) 53
  17. 17.Best estimate of 2224 ÷ 33? (a) 7400 (b) 74 (c) 740
  18. 18.Best estimate of 2723 ÷ 79? (a) 340 (b) 34 (c) 3400
  19. 19.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.9 (d) 6.8
  20. 20.Best estimate of 1129 ÷ 23? (a) 56 (b) 5600 (c) 560
  21. 21.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.6
  22. 22.Best estimate of 1251 ÷ 28? (a) 4200 (b) 42 (c) 420
  23. 23.Best estimate of 3811 ÷ 43? (a) 950 (b) 95 (c) 9500
  24. 24.Best estimate of 2587 ÷ 51? (a) 5200 (b) 520 (c) 52
  25. 25.Best estimate of 5694 ÷ 81? (a) 71 (b) 7100 (c) 710
  26. 26.Best estimate of 1653 ÷ 61? (a) 2800 (b) 280 (c) 28
  27. 27.Best estimate of 2866 ÷ 46? (a) 570 (b) 57 (c) 5700
  28. 28.Best estimate of 2493 ÷ 66? (a) 36 (b) 3600 (c) 360
  29. 29.√59 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.8 (d) 7.7
  30. 30.Best estimate of 832 ÷ 21? (a) 4200 (b) 420 (c) 42
  31. 31.√26 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 5.1
  32. 32.√48 to 1 decimal place? (a) 7.0 (b) 6.7 (c) 6.9 (d) 6.8
  33. 33.Best estimate of 6252 ÷ 86? (a) 690 (b) 69 (c) 6900
  34. 34.Best estimate of 1435 ÷ 53? (a) 29 (b) 290 (c) 2900
  35. 35.Best estimate of 1185 ÷ 21? (a) 5900 (b) 59 (c) 590
  36. 36.√92 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 9.6
  37. 37.√89 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.5 (d) 9.7
  38. 38.Best estimate of 3576 ÷ 53? (a) 7200 (b) 720 (c) 72
  39. 39.Best estimate of 2404 ÷ 82? (a) 3000 (b) 30 (c) 300
  40. 40.Best estimate of 3320 ÷ 37? (a) 83 (b) 830 (c) 8300

Answer key

  1. 96
  2. 82
  3. 7.8
  4. 4.5
  5. 19
  6. 68
  7. 9.7
  8. 8.3
  9. 6.1
  10. 13
  11. 71
  12. 4.7
  13. 76
  14. 4.9
  15. 18
  16. 53
  17. 74
  18. 34
  19. 6.6
  20. 56
  21. 6.3
  22. 42
  23. 95
  24. 52
  25. 71
  26. 28
  27. 57
  28. 36
  29. 7.7
  30. 42
  31. 5.1
  32. 6.9
  33. 69
  34. 29
  35. 59
  36. 9.6
  37. 9.4
  38. 72
  39. 30
  40. 83

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