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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 915 · 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.√21 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  2. 2.√89 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.4 (d) 9.3
  3. 3.√45 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.7
  4. 4.√29 to 1 decimal place? (a) 5.7 (b) 5.4 (c) 5.6 (d) 5.5
  5. 5.Best estimate of 1677 ÷ 42? (a) 420 (b) 42 (c) 4200
  6. 6.√55 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.3 (d) 7.2
  7. 7.Best estimate of 6239 ÷ 67? (a) 89 (b) 890 (c) 8900
  8. 8.√38 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.3 (d) 6.4
  9. 9.√72 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5
  10. 10.√78 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 9.0
  11. 11.Best estimate of 6901 ÷ 84? (a) 86 (b) 8600 (c) 860
  12. 12.Best estimate of 1730 ÷ 34? (a) 5800 (b) 580 (c) 58
  13. 13.Best estimate of 381 ÷ 21? (a) 190 (b) 19 (c) 1900
  14. 14.√62 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.1 (d) 8.0
  15. 15.Best estimate of 5157 ÷ 73? (a) 7400 (b) 740 (c) 74
  16. 16.Best estimate of 889 ÷ 23? (a) 440 (b) 44 (c) 4400
  17. 17.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.9 (d) 5.7
  18. 18.√22 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.0 (d) 4.7
  19. 19.√28 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.5 (d) 5.6
  20. 20.Best estimate of 3324 ÷ 41? (a) 8300 (b) 830 (c) 83
  21. 21.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.3
  22. 22.Best estimate of 2137 ÷ 49? (a) 43 (b) 430 (c) 4300
  23. 23.Best estimate of 5927 ÷ 74? (a) 85 (b) 8500 (c) 850
  24. 24.Best estimate of 2242 ÷ 48? (a) 4500 (b) 45 (c) 450
  25. 25.Best estimate of 513 ÷ 38? (a) 130 (b) 13 (c) 1300
  26. 26.√32 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.6 (d) 5.5
  27. 27.√83 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.0 (d) 8.8
  28. 28.Best estimate of 8319 ÷ 87? (a) 920 (b) 9200 (c) 92
  29. 29.√59 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.5
  30. 30.√43 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.8 (d) 6.7
  31. 31.Best estimate of 3515 ÷ 58? (a) 59 (b) 5900 (c) 590
  32. 32.√71 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.3 (d) 8.4
  33. 33.Best estimate of 3422 ÷ 36? (a) 860 (b) 8600 (c) 86
  34. 34.Best estimate of 6067 ÷ 72? (a) 8700 (b) 870 (c) 87
  35. 35.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.6 (d) 9.7
  36. 36.Best estimate of 6555 ÷ 71? (a) 94 (b) 9400 (c) 940
  37. 37.Best estimate of 696 ÷ 46? (a) 140 (b) 14 (c) 1400
  38. 38.√70 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4
  39. 39.Best estimate of 1364 ÷ 89? (a) 15 (b) 1500 (c) 150
  40. 40.Best estimate of 2477 ÷ 32? (a) 830 (b) 8300 (c) 83

Answer key

  1. 4.6
  2. 9.4
  3. 6.7
  4. 5.4
  5. 42
  6. 7.4
  7. 89
  8. 6.2
  9. 8.5
  10. 8.8
  11. 86
  12. 58
  13. 19
  14. 7.9
  15. 74
  16. 44
  17. 5.8
  18. 4.7
  19. 5.3
  20. 83
  21. 9.6
  22. 43
  23. 85
  24. 45
  25. 13
  26. 5.7
  27. 9.1
  28. 92
  29. 7.7
  30. 6.6
  31. 59
  32. 8.4
  33. 86
  34. 87
  35. 9.8
  36. 94
  37. 14
  38. 8.4
  39. 15
  40. 83

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