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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 759 · 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.√34 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 5.8 (d) 6.0
  2. 2.Best estimate of 7335 ÷ 83? (a) 920 (b) 9200 (c) 92
  3. 3.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.7
  4. 4.√58 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.5
  5. 5.√82 to 1 decimal place? (a) 9.3 (b) 9.0 (c) 9.1 (d) 9.2
  6. 6.Best estimate of 2658 ÷ 43? (a) 660 (b) 6600 (c) 66
  7. 7.√74 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.7 (d) 8.6
  8. 8.Best estimate of 2282 ÷ 34? (a) 760 (b) 76 (c) 7600
  9. 9.Best estimate of 6198 ÷ 84? (a) 770 (b) 7700 (c) 77
  10. 10.√77 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.6 (d) 8.8
  11. 11.Best estimate of 6259 ÷ 72? (a) 8900 (b) 890 (c) 89
  12. 12.Best estimate of 3325 ÷ 37? (a) 8300 (b) 83 (c) 830
  13. 13.Best estimate of 3416 ÷ 39? (a) 85 (b) 850 (c) 8500
  14. 14.Best estimate of 2139 ÷ 26? (a) 7100 (b) 71 (c) 710
  15. 15.Best estimate of 2310 ÷ 74? (a) 3300 (b) 33 (c) 330
  16. 16.Best estimate of 872 ÷ 37? (a) 220 (b) 22 (c) 2200
  17. 17.Best estimate of 2152 ÷ 32? (a) 720 (b) 7200 (c) 72
  18. 18.Best estimate of 2323 ÷ 51? (a) 46 (b) 460 (c) 4600
  19. 19.Best estimate of 445 ÷ 22? (a) 2200 (b) 22 (c) 220
  20. 20.Best estimate of 6386 ÷ 82? (a) 800 (b) 80 (c) 8000
  21. 21.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.6 (d) 8.5
  22. 22.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2
  23. 23.Best estimate of 1731 ÷ 42? (a) 4300 (b) 43 (c) 430
  24. 24.Best estimate of 4578 ÷ 66? (a) 650 (b) 6500 (c) 65
  25. 25.Best estimate of 1611 ÷ 21? (a) 8100 (b) 810 (c) 81
  26. 26.Best estimate of 2871 ÷ 47? (a) 57 (b) 5700 (c) 570
  27. 27.√41 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.4
  28. 28.Best estimate of 5863 ÷ 87? (a) 650 (b) 6500 (c) 65
  29. 29.√61 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.8 (d) 7.7
  30. 30.Best estimate of 6769 ÷ 71? (a) 9700 (b) 97 (c) 970
  31. 31.Best estimate of 4894 ÷ 77? (a) 610 (b) 6100 (c) 61
  32. 32.Best estimate of 2771 ÷ 72? (a) 400 (b) 4000 (c) 40
  33. 33.Best estimate of 987 ÷ 66? (a) 1400 (b) 140 (c) 14
  34. 34.√32 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.8 (d) 5.7
  35. 35.Best estimate of 739 ÷ 39? (a) 18 (b) 1800 (c) 180
  36. 36.√84 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 8.9
  37. 37.Best estimate of 4661 ÷ 87? (a) 520 (b) 5200 (c) 52
  38. 38.Best estimate of 846 ÷ 32? (a) 28 (b) 2800 (c) 280
  39. 39.√23 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.9 (d) 4.7
  40. 40.Best estimate of 502 ÷ 24? (a) 250 (b) 25 (c) 2500

Answer key

  1. 5.8
  2. 92
  3. 6.5
  4. 7.6
  5. 9.1
  6. 66
  7. 8.6
  8. 76
  9. 77
  10. 8.8
  11. 89
  12. 83
  13. 85
  14. 71
  15. 33
  16. 22
  17. 72
  18. 46
  19. 22
  20. 80
  21. 8.3
  22. 6.3
  23. 43
  24. 65
  25. 81
  26. 57
  27. 6.4
  28. 65
  29. 7.8
  30. 97
  31. 61
  32. 40
  33. 14
  34. 5.7
  35. 18
  36. 9.2
  37. 52
  38. 28
  39. 4.8
  40. 25

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