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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 658 · 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 2239 ÷ 31? (a) 750 (b) 7500 (c) 75
  2. 2.√24 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.0 (d) 5.1
  3. 3.Best estimate of 3912 ÷ 52? (a) 7800 (b) 78 (c) 780
  4. 4.√98 to 1 decimal place? (a) 10.0 (b) 10.2 (c) 10.1 (d) 9.9
  5. 5.Best estimate of 4326 ÷ 64? (a) 7200 (b) 72 (c) 720
  6. 6.√74 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.7
  7. 7.√44 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.4 (d) 6.5
  8. 8.√21 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.4 (d) 4.7
  9. 9.Best estimate of 4374 ÷ 89? (a) 4900 (b) 49 (c) 490
  10. 10.√72 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.8
  11. 11.√78 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  12. 12.Best estimate of 660 ÷ 32? (a) 2200 (b) 220 (c) 22
  13. 13.Best estimate of 7011 ÷ 76? (a) 88 (b) 880 (c) 8800
  14. 14.Best estimate of 1126 ÷ 51? (a) 23 (b) 230 (c) 2300
  15. 15.√52 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.1 (d) 6.9
  16. 16.Best estimate of 1564 ÷ 26? (a) 520 (b) 5200 (c) 52
  17. 17.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  18. 18.√37 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.3 (d) 6.2
  19. 19.√42 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.2
  20. 20.√40 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.2
  21. 21.Best estimate of 2028 ÷ 32? (a) 68 (b) 6800 (c) 680
  22. 22.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  23. 23.Best estimate of 5028 ÷ 82? (a) 6300 (b) 63 (c) 630
  24. 24.√61 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  25. 25.√26 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.0
  26. 26.Best estimate of 2563 ÷ 42? (a) 640 (b) 64 (c) 6400
  27. 27.Best estimate of 2373 ÷ 29? (a) 790 (b) 7900 (c) 79
  28. 28.Best estimate of 3844 ÷ 64? (a) 64 (b) 640 (c) 6400
  29. 29.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 9.7
  30. 30.Best estimate of 1869 ÷ 24? (a) 93 (b) 930 (c) 9300
  31. 31.√82 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  32. 32.Best estimate of 2267 ÷ 26? (a) 760 (b) 76 (c) 7600
  33. 33.Best estimate of 1216 ÷ 24? (a) 61 (b) 6100 (c) 610
  34. 34.Best estimate of 4616 ÷ 77? (a) 580 (b) 5800 (c) 58
  35. 35.Best estimate of 2482 ÷ 74? (a) 350 (b) 3500 (c) 35
  36. 36.Best estimate of 6896 ÷ 86? (a) 770 (b) 7700 (c) 77
  37. 37.Best estimate of 5935 ÷ 69? (a) 850 (b) 8500 (c) 85
  38. 38.√92 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.6 (d) 9.5
  39. 39.Best estimate of 3477 ÷ 84? (a) 4300 (b) 43 (c) 430
  40. 40.Best estimate of 3085 ÷ 36? (a) 77 (b) 7700 (c) 770

Answer key

  1. 75
  2. 4.9
  3. 78
  4. 9.9
  5. 72
  6. 8.6
  7. 6.6
  8. 4.6
  9. 49
  10. 8.5
  11. 8.8
  12. 22
  13. 88
  14. 23
  15. 7.2
  16. 52
  17. 4.5
  18. 6.1
  19. 6.5
  20. 6.3
  21. 68
  22. 5.7
  23. 63
  24. 7.8
  25. 5.1
  26. 64
  27. 79
  28. 64
  29. 9.8
  30. 93
  31. 9.1
  32. 76
  33. 61
  34. 58
  35. 35
  36. 77
  37. 85
  38. 9.6
  39. 43
  40. 77

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