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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 736 · 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 3367 ÷ 51? (a) 67 (b) 670 (c) 6700
  2. 2.√72 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.6 (d) 8.7
  3. 3.Best estimate of 1821 ÷ 27? (a) 6100 (b) 61 (c) 610
  4. 4.Best estimate of 1789 ÷ 26? (a) 600 (b) 6000 (c) 60
  5. 5.Best estimate of 6487 ÷ 82? (a) 81 (b) 8100 (c) 810
  6. 6.Best estimate of 732 ÷ 32? (a) 2400 (b) 24 (c) 240
  7. 7.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 6.3
  8. 8.√96 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.9
  9. 9.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.0
  10. 10.√78 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.5
  11. 11.Best estimate of 6132 ÷ 64? (a) 10200 (b) 102 (c) 1020
  12. 12.Best estimate of 2479 ÷ 69? (a) 350 (b) 35 (c) 3500
  13. 13.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.0 (d) 5.2
  14. 14.Best estimate of 423 ÷ 28? (a) 14 (b) 1400 (c) 140
  15. 15.Best estimate of 5059 ÷ 57? (a) 84 (b) 840 (c) 8400
  16. 16.Best estimate of 5401 ÷ 78? (a) 680 (b) 68 (c) 6800
  17. 17.Best estimate of 2056 ÷ 32? (a) 690 (b) 6900 (c) 69
  18. 18.Best estimate of 2048 ÷ 71? (a) 2900 (b) 290 (c) 29
  19. 19.Best estimate of 5943 ÷ 71? (a) 850 (b) 85 (c) 8500
  20. 20.√87 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  21. 21.Best estimate of 2486 ÷ 33? (a) 8300 (b) 830 (c) 83
  22. 22.√53 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.0
  23. 23.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.8 (d) 5.9
  24. 24.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  25. 25.√63 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 7.6
  26. 26.√38 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.4
  27. 27.Best estimate of 570 ÷ 22? (a) 290 (b) 2900 (c) 29
  28. 28.√40 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.5 (d) 6.4
  29. 29.Best estimate of 769 ÷ 38? (a) 190 (b) 1900 (c) 19
  30. 30.Best estimate of 1499 ÷ 29? (a) 5000 (b) 500 (c) 50
  31. 31.Best estimate of 3072 ÷ 82? (a) 38 (b) 3800 (c) 380
  32. 32.Best estimate of 2616 ÷ 29? (a) 8700 (b) 87 (c) 870
  33. 33.Best estimate of 3265 ÷ 54? (a) 6500 (b) 650 (c) 65
  34. 34.Best estimate of 3261 ÷ 66? (a) 470 (b) 4700 (c) 47
  35. 35.√24 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.8 (d) 4.6
  36. 36.Best estimate of 5134 ÷ 73? (a) 730 (b) 7300 (c) 73
  37. 37.√98 to 1 decimal place? (a) 10.2 (b) 10.1 (c) 10.0 (d) 9.9
  38. 38.Best estimate of 335 ÷ 26? (a) 1100 (b) 11 (c) 110
  39. 39.Best estimate of 4456 ÷ 78? (a) 56 (b) 5600 (c) 560
  40. 40.√31 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.8 (d) 5.7

Answer key

  1. 67
  2. 8.5
  3. 61
  4. 60
  5. 81
  6. 24
  7. 6.1
  8. 9.8
  9. 9.1
  10. 8.8
  11. 102
  12. 35
  13. 5.1
  14. 14
  15. 84
  16. 68
  17. 69
  18. 29
  19. 85
  20. 9.3
  21. 83
  22. 7.3
  23. 5.8
  24. 8.4
  25. 7.9
  26. 6.2
  27. 29
  28. 6.3
  29. 19
  30. 50
  31. 38
  32. 87
  33. 65
  34. 47
  35. 4.9
  36. 73
  37. 9.9
  38. 11
  39. 56
  40. 5.6

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