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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 26 · 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.√23 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.6 (d) 4.7
  2. 2.√61 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.5 (d) 7.7
  3. 3.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.8 (d) 4.9
  4. 4.Best estimate of 3843 ÷ 56? (a) 64 (b) 640 (c) 6400
  5. 5.Best estimate of 5433 ÷ 68? (a) 780 (b) 7800 (c) 78
  6. 6.Best estimate of 3408 ÷ 38? (a) 8500 (b) 850 (c) 85
  7. 7.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.7 (d) 7.5
  8. 8.Best estimate of 1212 ÷ 74? (a) 17 (b) 1700 (c) 170
  9. 9.√79 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 9.0
  10. 10.√41 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.3
  11. 11.Best estimate of 3219 ÷ 89? (a) 3600 (b) 36 (c) 360
  12. 12.Best estimate of 2577 ÷ 29? (a) 8600 (b) 860 (c) 86
  13. 13.Best estimate of 6468 ÷ 86? (a) 7200 (b) 720 (c) 72
  14. 14.Best estimate of 3461 ÷ 72? (a) 49 (b) 4900 (c) 490
  15. 15.Best estimate of 1438 ÷ 29? (a) 480 (b) 48 (c) 4800
  16. 16.√40 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.4 (d) 6.5
  17. 17.Best estimate of 6661 ÷ 72? (a) 9500 (b) 95 (c) 950
  18. 18.√58 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.5 (d) 7.6
  19. 19.Best estimate of 1805 ÷ 63? (a) 300 (b) 30 (c) 3000
  20. 20.√22 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 5.0 (d) 4.8
  21. 21.Best estimate of 755 ÷ 31? (a) 2500 (b) 25 (c) 250
  22. 22.√32 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.7 (d) 5.9
  23. 23.Best estimate of 3366 ÷ 38? (a) 84 (b) 8400 (c) 840
  24. 24.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.2 (d) 7.1
  25. 25.Best estimate of 1961 ÷ 82? (a) 2500 (b) 250 (c) 25
  26. 26.Best estimate of 2352 ÷ 43? (a) 5900 (b) 59 (c) 590
  27. 27.√28 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.6
  28. 28.√51 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2
  29. 29.√66 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  30. 30.Best estimate of 1364 ÷ 32? (a) 450 (b) 4500 (c) 45
  31. 31.√29 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.4 (d) 5.5
  32. 32.Best estimate of 5380 ÷ 67? (a) 7700 (b) 77 (c) 770
  33. 33.Best estimate of 5791 ÷ 78? (a) 7200 (b) 72 (c) 720
  34. 34.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 5.7
  35. 35.Best estimate of 3768 ÷ 53? (a) 7500 (b) 750 (c) 75
  36. 36.Best estimate of 1730 ÷ 22? (a) 8700 (b) 870 (c) 87
  37. 37.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 10.1
  38. 38.Best estimate of 2256 ÷ 34? (a) 750 (b) 7500 (c) 75
  39. 39.√27 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.0 (d) 5.2
  40. 40.Best estimate of 3484 ÷ 56? (a) 580 (b) 5800 (c) 58

Answer key

  1. 4.8
  2. 7.8
  3. 5.1
  4. 64
  5. 78
  6. 85
  7. 7.4
  8. 17
  9. 8.9
  10. 6.4
  11. 36
  12. 86
  13. 72
  14. 49
  15. 48
  16. 6.3
  17. 95
  18. 7.6
  19. 30
  20. 4.7
  21. 25
  22. 5.7
  23. 84
  24. 7.3
  25. 25
  26. 59
  27. 5.3
  28. 7.1
  29. 8.1
  30. 45
  31. 5.4
  32. 77
  33. 72
  34. 5.8
  35. 75
  36. 87
  37. 9.9
  38. 75
  39. 5.2
  40. 58

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