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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 140 · 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 2677 ÷ 42? (a) 67 (b) 670 (c) 6700
  2. 2.Best estimate of 1789 ÷ 27? (a) 6000 (b) 600 (c) 60
  3. 3.Best estimate of 3775 ÷ 49? (a) 76 (b) 7600 (c) 760
  4. 4.Best estimate of 402 ÷ 29? (a) 130 (b) 1300 (c) 13
  5. 5.√59 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.7
  6. 6.√27 to 1 decimal place? (a) 4.9 (b) 5.2 (c) 5.1 (d) 5.0
  7. 7.√47 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 6.8 (d) 7.0
  8. 8.Best estimate of 850 ÷ 26? (a) 280 (b) 28 (c) 2800
  9. 9.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  10. 10.Best estimate of 2265 ÷ 42? (a) 57 (b) 570 (c) 5700
  11. 11.Best estimate of 5122 ÷ 71? (a) 7300 (b) 73 (c) 730
  12. 12.√79 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 8.9
  13. 13.Best estimate of 1927 ÷ 41? (a) 480 (b) 4800 (c) 48
  14. 14.Best estimate of 6949 ÷ 89? (a) 77 (b) 7700 (c) 770
  15. 15.√84 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.3 (d) 9.1
  16. 16.Best estimate of 3636 ÷ 52? (a) 73 (b) 730 (c) 7300
  17. 17.Best estimate of 4988 ÷ 56? (a) 830 (b) 83 (c) 8300
  18. 18.√23 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.8 (d) 4.5
  19. 19.Best estimate of 1901 ÷ 23? (a) 95 (b) 950 (c) 9500
  20. 20.Best estimate of 1472 ÷ 21? (a) 74 (b) 7400 (c) 740
  21. 21.Best estimate of 1590 ÷ 87? (a) 180 (b) 1800 (c) 18
  22. 22.Best estimate of 2114 ÷ 34? (a) 70 (b) 700 (c) 7000
  23. 23.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.5
  24. 24.Best estimate of 5469 ÷ 62? (a) 910 (b) 91 (c) 9100
  25. 25.Best estimate of 631 ÷ 46? (a) 13 (b) 1300 (c) 130
  26. 26.√44 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.9
  27. 27.Best estimate of 5986 ÷ 88? (a) 6700 (b) 670 (c) 67
  28. 28.Best estimate of 3181 ÷ 81? (a) 40 (b) 4000 (c) 400
  29. 29.Best estimate of 757 ÷ 33? (a) 2500 (b) 250 (c) 25
  30. 30.Best estimate of 3871 ÷ 89? (a) 4300 (b) 430 (c) 43
  31. 31.Best estimate of 881 ÷ 34? (a) 29 (b) 2900 (c) 290
  32. 32.Best estimate of 1920 ÷ 22? (a) 960 (b) 9600 (c) 96
  33. 33.Best estimate of 2348 ÷ 36? (a) 5900 (b) 59 (c) 590
  34. 34.Best estimate of 5754 ÷ 88? (a) 6400 (b) 640 (c) 64
  35. 35.Best estimate of 1588 ÷ 89? (a) 18 (b) 180 (c) 1800
  36. 36.Best estimate of 1206 ÷ 71? (a) 170 (b) 17 (c) 1700
  37. 37.√42 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.5 (d) 6.6
  38. 38.Best estimate of 1783 ÷ 26? (a) 590 (b) 59 (c) 5900
  39. 39.Best estimate of 3513 ÷ 52? (a) 70 (b) 700 (c) 7000
  40. 40.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6

Answer key

  1. 67
  2. 60
  3. 76
  4. 13
  5. 7.7
  6. 5.2
  7. 6.9
  8. 28
  9. 8.1
  10. 57
  11. 73
  12. 8.9
  13. 48
  14. 77
  15. 9.2
  16. 73
  17. 83
  18. 4.8
  19. 95
  20. 74
  21. 18
  22. 70
  23. 6.2
  24. 91
  25. 13
  26. 6.6
  27. 67
  28. 40
  29. 25
  30. 43
  31. 29
  32. 96
  33. 59
  34. 64
  35. 18
  36. 17
  37. 6.5
  38. 59
  39. 70
  40. 9.7

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