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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 787 · 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 2471 ÷ 88? (a) 270 (b) 27 (c) 2700
  2. 2.√26 to 1 decimal place? (a) 5.3 (b) 5.0 (c) 5.1 (d) 5.2
  3. 3.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.7 (d) 5.6
  4. 4.Best estimate of 2276 ÷ 72? (a) 3300 (b) 33 (c) 330
  5. 5.√28 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  6. 6.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  7. 7.√42 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.5
  8. 8.Best estimate of 696 ÷ 24? (a) 3500 (b) 350 (c) 35
  9. 9.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.7 (d) 7.5
  10. 10.Best estimate of 2459 ÷ 38? (a) 61 (b) 6100 (c) 610
  11. 11.Best estimate of 7026 ÷ 82? (a) 8800 (b) 880 (c) 88
  12. 12.√21 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.9 (d) 4.8
  13. 13.Best estimate of 6803 ÷ 82? (a) 85 (b) 8500 (c) 850
  14. 14.Best estimate of 3593 ÷ 39? (a) 900 (b) 9000 (c) 90
  15. 15.√37 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2
  16. 16.√79 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.6 (d) 8.8
  17. 17.Best estimate of 1741 ÷ 71? (a) 2500 (b) 250 (c) 25
  18. 18.Best estimate of 574 ÷ 47? (a) 110 (b) 11 (c) 1100
  19. 19.√53 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.0 (d) 7.1
  20. 20.√43 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.5 (d) 6.6
  21. 21.√34 to 1 decimal place? (a) 5.9 (b) 5.6 (c) 5.7 (d) 5.8
  22. 22.Best estimate of 2072 ÷ 63? (a) 35 (b) 3500 (c) 350
  23. 23.√24 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.0 (d) 5.2
  24. 24.Best estimate of 1421 ÷ 57? (a) 24 (b) 2400 (c) 240
  25. 25.Best estimate of 4626 ÷ 74? (a) 660 (b) 6600 (c) 66
  26. 26.√84 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.1 (d) 9.3
  27. 27.√51 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 6.9
  28. 28.Best estimate of 7654 ÷ 87? (a) 85 (b) 850 (c) 8500
  29. 29.√70 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.5 (d) 8.7
  30. 30.√87 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.3 (d) 9.1
  31. 31.√38 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.0 (d) 6.3
  32. 32.√63 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 8.1
  33. 33.Best estimate of 2757 ÷ 58? (a) 46 (b) 4600 (c) 460
  34. 34.√20 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.3 (d) 4.4
  35. 35.Best estimate of 3787 ÷ 49? (a) 76 (b) 7600 (c) 760
  36. 36.Best estimate of 7329 ÷ 87? (a) 810 (b) 8100 (c) 81
  37. 37.√50 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  38. 38.√23 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 4.8
  39. 39.√44 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  40. 40.Best estimate of 715 ÷ 41? (a) 18 (b) 1800 (c) 180

Answer key

  1. 27
  2. 5.1
  3. 5.5
  4. 33
  5. 5.3
  6. 8.1
  7. 6.5
  8. 35
  9. 7.6
  10. 61
  11. 88
  12. 4.6
  13. 85
  14. 90
  15. 6.1
  16. 8.9
  17. 25
  18. 11
  19. 7.3
  20. 6.6
  21. 5.8
  22. 35
  23. 4.9
  24. 24
  25. 66
  26. 9.2
  27. 7.1
  28. 85
  29. 8.4
  30. 9.3
  31. 6.2
  32. 7.9
  33. 46
  34. 4.5
  35. 76
  36. 81
  37. 7.1
  38. 4.8
  39. 6.6
  40. 18

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