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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 696 · 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 1919 ÷ 81? (a) 2400 (b) 240 (c) 24
  2. 2.√29 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.4
  3. 3.√83 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 8.9
  4. 4.Best estimate of 2745 ÷ 36? (a) 690 (b) 6900 (c) 69
  5. 5.√89 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.5 (d) 9.4
  6. 6.Best estimate of 763 ÷ 59? (a) 130 (b) 1300 (c) 13
  7. 7.√63 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.9
  8. 8.Best estimate of 953 ÷ 52? (a) 190 (b) 1900 (c) 19
  9. 9.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 10.2 (d) 9.9
  10. 10.√59 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 7.7
  11. 11.Best estimate of 3091 ÷ 41? (a) 770 (b) 7700 (c) 77
  12. 12.Best estimate of 1815 ÷ 73? (a) 26 (b) 2600 (c) 260
  13. 13.Best estimate of 4256 ÷ 61? (a) 7100 (b) 71 (c) 710
  14. 14.Best estimate of 4628 ÷ 56? (a) 7700 (b) 770 (c) 77
  15. 15.Best estimate of 1161 ÷ 76? (a) 1500 (b) 150 (c) 15
  16. 16.Best estimate of 3998 ÷ 46? (a) 8000 (b) 800 (c) 80
  17. 17.√61 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.9 (d) 7.8
  18. 18.Best estimate of 1945 ÷ 42? (a) 49 (b) 4900 (c) 490
  19. 19.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.0
  20. 20.√85 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.1 (d) 9.3
  21. 21.Best estimate of 777 ÷ 26? (a) 26 (b) 2600 (c) 260
  22. 22.Best estimate of 3184 ÷ 76? (a) 400 (b) 4000 (c) 40
  23. 23.√79 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  24. 24.√21 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.9
  25. 25.√67 to 1 decimal place? (a) 8.0 (b) 8.3 (c) 8.2 (d) 8.1
  26. 26.Best estimate of 1707 ÷ 43? (a) 43 (b) 4300 (c) 430
  27. 27.Best estimate of 1532 ÷ 89? (a) 17 (b) 170 (c) 1700
  28. 28.Best estimate of 982 ÷ 76? (a) 12 (b) 1200 (c) 120
  29. 29.√28 to 1 decimal place? (a) 5.6 (b) 5.3 (c) 5.4 (d) 5.5
  30. 30.Best estimate of 6636 ÷ 84? (a) 83 (b) 8300 (c) 830
  31. 31.√65 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.1 (d) 8.0
  32. 32.Best estimate of 2893 ÷ 33? (a) 9600 (b) 96 (c) 960
  33. 33.Best estimate of 1194 ÷ 26? (a) 40 (b) 400 (c) 4000
  34. 34.Best estimate of 477 ÷ 24? (a) 240 (b) 2400 (c) 24
  35. 35.√74 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  36. 36.Best estimate of 3432 ÷ 38? (a) 860 (b) 86 (c) 8600
  37. 37.Best estimate of 2575 ÷ 82? (a) 320 (b) 32 (c) 3200
  38. 38.√45 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.5 (d) 6.7
  39. 39.Best estimate of 6268 ÷ 76? (a) 78 (b) 7800 (c) 780
  40. 40.√82 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0

Answer key

  1. 24
  2. 5.4
  3. 9.1
  4. 69
  5. 9.4
  6. 13
  7. 7.9
  8. 19
  9. 9.9
  10. 7.7
  11. 77
  12. 26
  13. 71
  14. 77
  15. 15
  16. 80
  17. 7.8
  18. 49
  19. 5.1
  20. 9.2
  21. 26
  22. 40
  23. 8.9
  24. 4.6
  25. 8.2
  26. 43
  27. 17
  28. 12
  29. 5.3
  30. 83
  31. 8.1
  32. 96
  33. 40
  34. 24
  35. 8.6
  36. 86
  37. 32
  38. 6.7
  39. 78
  40. 9.1

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