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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 533 · 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.√42 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.2 (d) 6.4
  2. 2.√47 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.2 (d) 7.0
  3. 3.√67 to 1 decimal place? (a) 8.2 (b) 8.5 (c) 8.3 (d) 8.4
  4. 4.√23 to 1 decimal place? (a) 4.6 (b) 4.9 (c) 4.8 (d) 4.7
  5. 5.Best estimate of 2666 ÷ 76? (a) 330 (b) 3300 (c) 33
  6. 6.Best estimate of 1963 ÷ 81? (a) 2500 (b) 25 (c) 250
  7. 7.Best estimate of 7679 ÷ 86? (a) 85 (b) 8500 (c) 850
  8. 8.√35 to 1 decimal place? (a) 5.9 (b) 5.6 (c) 5.8 (d) 5.7
  9. 9.Best estimate of 5968 ÷ 72? (a) 8500 (b) 850 (c) 85
  10. 10.√38 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.4
  11. 11.Best estimate of 1658 ÷ 21? (a) 830 (b) 8300 (c) 83
  12. 12.Best estimate of 1134 ÷ 78? (a) 1400 (b) 14 (c) 140
  13. 13.√84 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  14. 14.Best estimate of 835 ÷ 27? (a) 28 (b) 280 (c) 2800
  15. 15.Best estimate of 4375 ÷ 56? (a) 7300 (b) 73 (c) 730
  16. 16.√44 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  17. 17.Best estimate of 2812 ÷ 78? (a) 35 (b) 3500 (c) 350
  18. 18.√34 to 1 decimal place? (a) 6.1 (b) 5.8 (c) 5.9 (d) 6.0
  19. 19.√45 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.5 (d) 6.6
  20. 20.√75 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.8
  21. 21.Best estimate of 640 ÷ 32? (a) 21 (b) 210 (c) 2100
  22. 22.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.5
  23. 23.Best estimate of 1071 ÷ 88? (a) 120 (b) 1200 (c) 12
  24. 24.Best estimate of 5240 ÷ 79? (a) 66 (b) 6600 (c) 660
  25. 25.Best estimate of 6378 ÷ 82? (a) 8000 (b) 80 (c) 800
  26. 26.√87 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.3
  27. 27.√29 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.4
  28. 28.√24 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.0 (d) 4.9
  29. 29.Best estimate of 4962 ÷ 58? (a) 8300 (b) 83 (c) 830
  30. 30.Best estimate of 1324 ÷ 87? (a) 150 (b) 15 (c) 1500
  31. 31.√30 to 1 decimal place? (a) 5.5 (b) 5.8 (c) 5.6 (d) 5.7
  32. 32.Best estimate of 2925 ÷ 34? (a) 980 (b) 9800 (c) 98
  33. 33.Best estimate of 1845 ÷ 24? (a) 920 (b) 9200 (c) 92
  34. 34.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  35. 35.√26 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 5.1 (d) 5.2
  36. 36.Best estimate of 2650 ÷ 48? (a) 5300 (b) 530 (c) 53
  37. 37.Best estimate of 3666 ÷ 72? (a) 52 (b) 520 (c) 5200
  38. 38.Best estimate of 1815 ÷ 87? (a) 20 (b) 2000 (c) 200
  39. 39.√28 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.6 (d) 5.5
  40. 40.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.3 (d) 7.4

Answer key

  1. 6.5
  2. 6.9
  3. 8.2
  4. 4.8
  5. 33
  6. 25
  7. 85
  8. 5.9
  9. 85
  10. 6.2
  11. 83
  12. 14
  13. 9.2
  14. 28
  15. 73
  16. 6.6
  17. 35
  18. 5.8
  19. 6.7
  20. 8.7
  21. 21
  22. 7.2
  23. 12
  24. 66
  25. 80
  26. 9.3
  27. 5.4
  28. 4.9
  29. 83
  30. 15
  31. 5.5
  32. 98
  33. 92
  34. 9.1
  35. 5.1
  36. 53
  37. 52
  38. 20
  39. 5.3
  40. 7.6

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