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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 758 · 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 2390 ÷ 84? (a) 300 (b) 30 (c) 3000
  2. 2.Best estimate of 2659 ÷ 53? (a) 53 (b) 530 (c) 5300
  3. 3.Best estimate of 2981 ÷ 36? (a) 75 (b) 750 (c) 7500
  4. 4.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 9.7
  5. 5.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.8
  6. 6.√74 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.9 (d) 8.7
  7. 7.√89 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.6 (d) 9.4
  8. 8.Best estimate of 2129 ÷ 42? (a) 530 (b) 5300 (c) 53
  9. 9.√47 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  10. 10.Best estimate of 1865 ÷ 27? (a) 62 (b) 6200 (c) 620
  11. 11.√37 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.0 (d) 6.2
  12. 12.√71 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.2
  13. 13.√40 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.2
  14. 14.√63 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  15. 15.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.9 (d) 7.8
  16. 16.Best estimate of 1162 ÷ 28? (a) 390 (b) 39 (c) 3900
  17. 17.√83 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0
  18. 18.Best estimate of 2760 ÷ 83? (a) 350 (b) 3500 (c) 35
  19. 19.√23 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.8 (d) 4.7
  20. 20.√34 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.5 (d) 5.6
  21. 21.Best estimate of 3622 ÷ 82? (a) 45 (b) 450 (c) 4500
  22. 22.Best estimate of 1568 ÷ 34? (a) 52 (b) 520 (c) 5200
  23. 23.Best estimate of 2339 ÷ 32? (a) 780 (b) 78 (c) 7800
  24. 24.√85 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.1 (d) 9.3
  25. 25.Best estimate of 2406 ÷ 63? (a) 40 (b) 400 (c) 4000
  26. 26.Best estimate of 2141 ÷ 62? (a) 3600 (b) 36 (c) 360
  27. 27.√21 to 1 decimal place? (a) 4.4 (b) 4.6 (c) 4.5 (d) 4.3
  28. 28.√59 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.4
  29. 29.Best estimate of 3138 ÷ 44? (a) 780 (b) 7800 (c) 78
  30. 30.Best estimate of 2444 ÷ 36? (a) 610 (b) 6100 (c) 61
  31. 31.Best estimate of 1782 ÷ 59? (a) 300 (b) 3000 (c) 30
  32. 32.√88 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  33. 33.Best estimate of 523 ÷ 37? (a) 1300 (b) 13 (c) 130
  34. 34.Best estimate of 6907 ÷ 76? (a) 8600 (b) 86 (c) 860
  35. 35.Best estimate of 2255 ÷ 46? (a) 450 (b) 45 (c) 4500
  36. 36.Best estimate of 4936 ÷ 73? (a) 710 (b) 7100 (c) 71
  37. 37.Best estimate of 743 ÷ 33? (a) 250 (b) 2500 (c) 25
  38. 38.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  39. 39.Best estimate of 697 ÷ 28? (a) 2300 (b) 230 (c) 23
  40. 40.Best estimate of 1669 ÷ 36? (a) 4200 (b) 42 (c) 420

Answer key

  1. 30
  2. 53
  3. 75
  4. 9.8
  5. 9.6
  6. 8.6
  7. 9.4
  8. 53
  9. 6.9
  10. 62
  11. 6.1
  12. 8.4
  13. 6.3
  14. 7.9
  15. 8.1
  16. 39
  17. 9.1
  18. 35
  19. 4.8
  20. 5.8
  21. 45
  22. 52
  23. 78
  24. 9.2
  25. 40
  26. 36
  27. 4.6
  28. 7.7
  29. 78
  30. 61
  31. 30
  32. 9.4
  33. 13
  34. 86
  35. 45
  36. 71
  37. 25
  38. 5.6
  39. 23
  40. 42

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