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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 919 · 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.√50 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 7.1 (d) 6.9
  2. 2.√34 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 5.8 (d) 6.0
  3. 3.Best estimate of 3861 ÷ 46? (a) 770 (b) 7700 (c) 77
  4. 4.Best estimate of 5921 ÷ 89? (a) 660 (b) 66 (c) 6600
  5. 5.√67 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.4 (d) 8.5
  6. 6.√51 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.1 (d) 7.3
  7. 7.Best estimate of 2391 ÷ 82? (a) 300 (b) 3000 (c) 30
  8. 8.√71 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.7
  9. 9.Best estimate of 6621 ÷ 83? (a) 8300 (b) 83 (c) 830
  10. 10.√75 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.8 (d) 8.7
  11. 11.Best estimate of 4067 ÷ 49? (a) 8100 (b) 810 (c) 81
  12. 12.Best estimate of 785 ÷ 28? (a) 260 (b) 2600 (c) 26
  13. 13.√92 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.7
  14. 14.Best estimate of 1716 ÷ 32? (a) 570 (b) 5700 (c) 57
  15. 15.√26 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.3 (d) 5.1
  16. 16.Best estimate of 1737 ÷ 21? (a) 87 (b) 870 (c) 8700
  17. 17.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  18. 18.Best estimate of 1832 ÷ 76? (a) 2300 (b) 23 (c) 230
  19. 19.√42 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.4 (d) 6.6
  20. 20.Best estimate of 3375 ÷ 39? (a) 84 (b) 8400 (c) 840
  21. 21.√38 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 6.2
  22. 22.Best estimate of 3504 ÷ 46? (a) 7000 (b) 70 (c) 700
  23. 23.Best estimate of 851 ÷ 61? (a) 140 (b) 1400 (c) 14
  24. 24.Best estimate of 5767 ÷ 64? (a) 9600 (b) 96 (c) 960
  25. 25.√77 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  26. 26.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 7.7
  27. 27.√69 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.3
  28. 28.Best estimate of 1329 ÷ 26? (a) 4400 (b) 44 (c) 440
  29. 29.√44 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 6.6
  30. 30.Best estimate of 4399 ÷ 57? (a) 73 (b) 730 (c) 7300
  31. 31.Best estimate of 843 ÷ 23? (a) 42 (b) 4200 (c) 420
  32. 32.Best estimate of 5031 ÷ 64? (a) 8400 (b) 840 (c) 84
  33. 33.Best estimate of 3849 ÷ 83? (a) 480 (b) 48 (c) 4800
  34. 34.Best estimate of 2276 ÷ 58? (a) 38 (b) 3800 (c) 380
  35. 35.√58 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.9 (d) 7.7
  36. 36.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.2 (d) 6.3
  37. 37.√65 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  38. 38.Best estimate of 1223 ÷ 34? (a) 4100 (b) 410 (c) 41
  39. 39.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  40. 40.Best estimate of 4484 ÷ 56? (a) 7500 (b) 750 (c) 75

Answer key

  1. 7.1
  2. 5.8
  3. 77
  4. 66
  5. 8.2
  6. 7.1
  7. 30
  8. 8.4
  9. 83
  10. 8.7
  11. 81
  12. 26
  13. 9.6
  14. 57
  15. 5.1
  16. 87
  17. 8.6
  18. 23
  19. 6.5
  20. 84
  21. 6.2
  22. 70
  23. 14
  24. 96
  25. 8.8
  26. 7.8
  27. 8.3
  28. 44
  29. 6.6
  30. 73
  31. 42
  32. 84
  33. 48
  34. 38
  35. 7.6
  36. 6.3
  37. 8.1
  38. 41
  39. 9.1
  40. 75

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