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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 367 · 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 2266 ÷ 74? (a) 3200 (b) 320 (c) 32
  2. 2.Best estimate of 589 ÷ 37? (a) 15 (b) 150 (c) 1500
  3. 3.Best estimate of 4888 ÷ 54? (a) 980 (b) 9800 (c) 98
  4. 4.Best estimate of 3069 ÷ 42? (a) 7700 (b) 77 (c) 770
  5. 5.√71 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.2 (d) 8.3
  6. 6.√76 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.7 (d) 8.6
  7. 7.√22 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.9 (d) 4.7
  8. 8.Best estimate of 7497 ÷ 87? (a) 83 (b) 8300 (c) 830
  9. 9.√83 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  10. 10.√88 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  11. 11.Best estimate of 1717 ÷ 41? (a) 430 (b) 4300 (c) 43
  12. 12.√50 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.2 (d) 7.1
  13. 13.Best estimate of 1978 ÷ 34? (a) 6600 (b) 660 (c) 66
  14. 14.Best estimate of 2989 ÷ 33? (a) 100 (b) 1000 (c) 10000
  15. 15.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.7
  16. 16.Best estimate of 2870 ÷ 88? (a) 320 (b) 3200 (c) 32
  17. 17.√75 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.9
  18. 18.Best estimate of 3165 ÷ 69? (a) 450 (b) 45 (c) 4500
  19. 19.Best estimate of 645 ÷ 37? (a) 160 (b) 1600 (c) 16
  20. 20.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  21. 21.√72 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.4 (d) 8.6
  22. 22.Best estimate of 1197 ÷ 82? (a) 15 (b) 150 (c) 1500
  23. 23.Best estimate of 1074 ÷ 33? (a) 3600 (b) 36 (c) 360
  24. 24.Best estimate of 1679 ÷ 36? (a) 420 (b) 42 (c) 4200
  25. 25.Best estimate of 1737 ÷ 21? (a) 8700 (b) 870 (c) 87
  26. 26.√28 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  27. 27.√82 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 8.8
  28. 28.Best estimate of 1544 ÷ 76? (a) 19 (b) 190 (c) 1900
  29. 29.√80 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  30. 30.Best estimate of 1138 ÷ 61? (a) 1900 (b) 19 (c) 190
  31. 31.Best estimate of 1787 ÷ 26? (a) 600 (b) 6000 (c) 60
  32. 32.√34 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 5.7
  33. 33.√38 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.3 (d) 6.2
  34. 34.√58 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 7.6
  35. 35.Best estimate of 903 ÷ 66? (a) 1300 (b) 13 (c) 130
  36. 36.Best estimate of 5525 ÷ 71? (a) 7900 (b) 790 (c) 79
  37. 37.Best estimate of 2403 ÷ 67? (a) 34 (b) 340 (c) 3400
  38. 38.Best estimate of 4001 ÷ 81? (a) 50 (b) 500 (c) 5000
  39. 39.Best estimate of 2381 ÷ 32? (a) 790 (b) 79 (c) 7900
  40. 40.Best estimate of 1591 ÷ 22? (a) 80 (b) 800 (c) 8000

Answer key

  1. 32
  2. 15
  3. 98
  4. 77
  5. 8.4
  6. 8.7
  7. 4.7
  8. 83
  9. 9.1
  10. 9.4
  11. 43
  12. 7.1
  13. 66
  14. 100
  15. 5.6
  16. 32
  17. 8.7
  18. 45
  19. 16
  20. 5.7
  21. 8.5
  22. 15
  23. 36
  24. 42
  25. 87
  26. 5.3
  27. 9.1
  28. 19
  29. 8.9
  30. 19
  31. 60
  32. 5.8
  33. 6.2
  34. 7.6
  35. 13
  36. 79
  37. 34
  38. 50
  39. 79
  40. 80

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