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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 962 · 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.√40 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.3 (d) 6.1
  2. 2.Best estimate of 3300 ÷ 52? (a) 6600 (b) 66 (c) 660
  3. 3.√35 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.8 (d) 5.9
  4. 4.Best estimate of 4567 ÷ 71? (a) 65 (b) 6500 (c) 650
  5. 5.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.8 (d) 6.9
  6. 6.Best estimate of 1411 ÷ 22? (a) 71 (b) 710 (c) 7100
  7. 7.Best estimate of 2275 ÷ 46? (a) 460 (b) 46 (c) 4600
  8. 8.Best estimate of 2451 ÷ 53? (a) 490 (b) 49 (c) 4900
  9. 9.Best estimate of 2925 ÷ 62? (a) 490 (b) 4900 (c) 49
  10. 10.Best estimate of 5916 ÷ 88? (a) 660 (b) 6600 (c) 66
  11. 11.Best estimate of 819 ÷ 64? (a) 14 (b) 140 (c) 1400
  12. 12.Best estimate of 6315 ÷ 88? (a) 700 (b) 70 (c) 7000
  13. 13.Best estimate of 1372 ÷ 34? (a) 460 (b) 4600 (c) 46
  14. 14.Best estimate of 2207 ÷ 24? (a) 11000 (b) 1100 (c) 110
  15. 15.Best estimate of 6126 ÷ 66? (a) 88 (b) 880 (c) 8800
  16. 16.√76 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.7
  17. 17.Best estimate of 2801 ÷ 78? (a) 350 (b) 35 (c) 3500
  18. 18.√79 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 8.7
  19. 19.Best estimate of 3611 ÷ 52? (a) 72 (b) 7200 (c) 720
  20. 20.Best estimate of 1912 ÷ 31? (a) 640 (b) 6400 (c) 64
  21. 21.√84 to 1 decimal place? (a) 9.2 (b) 9.5 (c) 9.4 (d) 9.3
  22. 22.Best estimate of 1546 ÷ 26? (a) 5200 (b) 520 (c) 52
  23. 23.√37 to 1 decimal place? (a) 6.1 (b) 5.8 (c) 5.9 (d) 6.0
  24. 24.Best estimate of 3662 ÷ 67? (a) 52 (b) 5200 (c) 520
  25. 25.Best estimate of 5684 ÷ 71? (a) 8100 (b) 81 (c) 810
  26. 26.√30 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4
  27. 27.√92 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.3
  28. 28.Best estimate of 5772 ÷ 62? (a) 9600 (b) 96 (c) 960
  29. 29.Best estimate of 2558 ÷ 32? (a) 8500 (b) 85 (c) 850
  30. 30.√31 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  31. 31.√27 to 1 decimal place? (a) 5.3 (b) 5.0 (c) 5.1 (d) 5.2
  32. 32.√83 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  33. 33.Best estimate of 4601 ÷ 48? (a) 920 (b) 92 (c) 9200
  34. 34.√69 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  35. 35.Best estimate of 4027 ÷ 56? (a) 67 (b) 670 (c) 6700
  36. 36.Best estimate of 984 ÷ 48? (a) 2000 (b) 200 (c) 20
  37. 37.√90 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.4 (d) 9.5
  38. 38.Best estimate of 5272 ÷ 68? (a) 75 (b) 7500 (c) 750
  39. 39.Best estimate of 772 ÷ 29? (a) 2600 (b) 26 (c) 260
  40. 40.Best estimate of 4512 ÷ 64? (a) 75 (b) 7500 (c) 750

Answer key

  1. 6.3
  2. 66
  3. 5.9
  4. 65
  5. 7.1
  6. 71
  7. 46
  8. 49
  9. 49
  10. 66
  11. 14
  12. 70
  13. 46
  14. 110
  15. 88
  16. 8.7
  17. 35
  18. 8.9
  19. 72
  20. 64
  21. 9.2
  22. 52
  23. 6.1
  24. 52
  25. 81
  26. 5.5
  27. 9.6
  28. 96
  29. 85
  30. 5.6
  31. 5.2
  32. 9.1
  33. 92
  34. 8.3
  35. 67
  36. 20
  37. 9.5
  38. 75
  39. 26
  40. 75

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