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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 688 · 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 2423 ÷ 27? (a) 81 (b) 810 (c) 8100
  2. 2.√31 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.5
  3. 3.√35 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.2 (d) 5.9
  4. 4.Best estimate of 1889 ÷ 33? (a) 630 (b) 63 (c) 6300
  5. 5.√61 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  6. 6.Best estimate of 6996 ÷ 77? (a) 8700 (b) 870 (c) 87
  7. 7.√71 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.3 (d) 8.5
  8. 8.Best estimate of 3338 ÷ 82? (a) 420 (b) 4200 (c) 42
  9. 9.Best estimate of 2880 ÷ 49? (a) 580 (b) 5800 (c) 58
  10. 10.Best estimate of 6197 ÷ 86? (a) 69 (b) 690 (c) 6900
  11. 11.Best estimate of 529 ÷ 28? (a) 1800 (b) 180 (c) 18
  12. 12.√82 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 8.8 (d) 9.0
  13. 13.√41 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.4 (d) 6.3
  14. 14.√44 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.6 (d) 6.5
  15. 15.Best estimate of 2772 ÷ 66? (a) 4000 (b) 400 (c) 40
  16. 16.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.4 (d) 8.5
  17. 17.√72 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.8 (d) 8.6
  18. 18.Best estimate of 1309 ÷ 31? (a) 440 (b) 44 (c) 4400
  19. 19.√70 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  20. 20.√40 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.1
  21. 21.Best estimate of 3053 ÷ 42? (a) 76 (b) 7600 (c) 760
  22. 22.Best estimate of 2143 ÷ 63? (a) 36 (b) 3600 (c) 360
  23. 23.Best estimate of 1155 ÷ 22? (a) 58 (b) 580 (c) 5800
  24. 24.Best estimate of 2335 ÷ 26? (a) 78 (b) 7800 (c) 780
  25. 25.Best estimate of 1768 ÷ 27? (a) 590 (b) 5900 (c) 59
  26. 26.√55 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.7 (d) 7.6
  27. 27.√26 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.1 (d) 5.4
  28. 28.√46 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.9 (d) 6.7
  29. 29.√52 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.1 (d) 7.0
  30. 30.Best estimate of 1214 ÷ 34? (a) 40 (b) 400 (c) 4000
  31. 31.Best estimate of 833 ÷ 32? (a) 2800 (b) 280 (c) 28
  32. 32.Best estimate of 1508 ÷ 29? (a) 5000 (b) 50 (c) 500
  33. 33.√27 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  34. 34.√96 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 10.0 (d) 9.9
  35. 35.√65 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  36. 36.√37 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.2 (d) 6.0
  37. 37.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.5
  38. 38.√32 to 1 decimal place? (a) 5.7 (b) 6.0 (c) 5.8 (d) 5.9
  39. 39.Best estimate of 1357 ÷ 81? (a) 1700 (b) 170 (c) 17
  40. 40.Best estimate of 928 ÷ 36? (a) 230 (b) 2300 (c) 23

Answer key

  1. 81
  2. 5.6
  3. 5.9
  4. 63
  5. 7.8
  6. 87
  7. 8.4
  8. 42
  9. 58
  10. 69
  11. 18
  12. 9.1
  13. 6.4
  14. 6.6
  15. 40
  16. 8.3
  17. 8.5
  18. 44
  19. 8.4
  20. 6.3
  21. 76
  22. 36
  23. 58
  24. 78
  25. 59
  26. 7.4
  27. 5.1
  28. 6.8
  29. 7.2
  30. 40
  31. 28
  32. 50
  33. 5.2
  34. 9.8
  35. 8.1
  36. 6.1
  37. 8.6
  38. 5.7
  39. 17
  40. 23

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