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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 460 · 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) 6.2 (b) 6.4 (c) 6.3 (d) 6.1
  2. 2.√23 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.6 (d) 4.8
  3. 3.√65 to 1 decimal place? (a) 8.0 (b) 8.3 (c) 8.2 (d) 8.1
  4. 4.Best estimate of 1313 ÷ 44? (a) 33 (b) 3300 (c) 330
  5. 5.Best estimate of 2790 ÷ 46? (a) 56 (b) 5600 (c) 560
  6. 6.√48 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 7.0
  7. 7.Best estimate of 5092 ÷ 61? (a) 850 (b) 85 (c) 8500
  8. 8.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  9. 9.√70 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.7 (d) 8.6
  10. 10.Best estimate of 3570 ÷ 53? (a) 7100 (b) 710 (c) 71
  11. 11.√62 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 8.2
  12. 12.√82 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 8.9 (d) 9.0
  13. 13.Best estimate of 482 ÷ 31? (a) 1600 (b) 160 (c) 16
  14. 14.Best estimate of 1567 ÷ 42? (a) 390 (b) 39 (c) 3900
  15. 15.√52 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.3 (d) 7.1
  16. 16.Best estimate of 1163 ÷ 52? (a) 23 (b) 230 (c) 2300
  17. 17.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.9
  18. 18.Best estimate of 1544 ÷ 24? (a) 7700 (b) 77 (c) 770
  19. 19.√74 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.3
  20. 20.√66 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 8.1 (d) 7.9
  21. 21.Best estimate of 5844 ÷ 69? (a) 830 (b) 83 (c) 8300
  22. 22.Best estimate of 1723 ÷ 86? (a) 190 (b) 1900 (c) 19
  23. 23.Best estimate of 861 ÷ 22? (a) 430 (b) 4300 (c) 43
  24. 24.Best estimate of 1756 ÷ 53? (a) 35 (b) 350 (c) 3500
  25. 25.Best estimate of 3234 ÷ 63? (a) 54 (b) 5400 (c) 540
  26. 26.Best estimate of 5239 ÷ 79? (a) 65 (b) 650 (c) 6500
  27. 27.Best estimate of 1535 ÷ 82? (a) 1900 (b) 190 (c) 19
  28. 28.Best estimate of 3874 ÷ 52? (a) 7700 (b) 77 (c) 770
  29. 29.Best estimate of 5566 ÷ 82? (a) 7000 (b) 70 (c) 700
  30. 30.Best estimate of 3209 ÷ 42? (a) 80 (b) 800 (c) 8000
  31. 31.Best estimate of 1725 ÷ 27? (a) 5800 (b) 580 (c) 58
  32. 32.Best estimate of 4342 ÷ 87? (a) 48 (b) 4800 (c) 480
  33. 33.Best estimate of 2529 ÷ 42? (a) 6300 (b) 63 (c) 630
  34. 34.Best estimate of 2286 ÷ 36? (a) 5700 (b) 57 (c) 570
  35. 35.Best estimate of 3480 ÷ 44? (a) 87 (b) 8700 (c) 870
  36. 36.Best estimate of 4925 ÷ 68? (a) 70 (b) 7000 (c) 700
  37. 37.Best estimate of 658 ÷ 41? (a) 16 (b) 1600 (c) 160
  38. 38.Best estimate of 4588 ÷ 64? (a) 76 (b) 760 (c) 7600
  39. 39.√32 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 5.6
  40. 40.√24 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.8 (d) 5.0

Answer key

  1. 6.3
  2. 4.8
  3. 8.1
  4. 33
  5. 56
  6. 6.9
  7. 85
  8. 5.8
  9. 8.4
  10. 71
  11. 7.9
  12. 9.1
  13. 16
  14. 39
  15. 7.2
  16. 23
  17. 9.7
  18. 77
  19. 8.6
  20. 8.1
  21. 83
  22. 19
  23. 43
  24. 35
  25. 54
  26. 65
  27. 19
  28. 77
  29. 70
  30. 80
  31. 58
  32. 48
  33. 63
  34. 57
  35. 87
  36. 70
  37. 16
  38. 76
  39. 5.7
  40. 4.9

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