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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 727 · 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.√77 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  2. 2.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.6
  3. 3.Best estimate of 3623 ÷ 67? (a) 5200 (b) 52 (c) 520
  4. 4.Best estimate of 760 ÷ 32? (a) 2500 (b) 25 (c) 250
  5. 5.Best estimate of 4634 ÷ 51? (a) 930 (b) 9300 (c) 93
  6. 6.√42 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.6
  7. 7.Best estimate of 2078 ÷ 32? (a) 6900 (b) 69 (c) 690
  8. 8.Best estimate of 743 ÷ 32? (a) 250 (b) 2500 (c) 25
  9. 9.Best estimate of 4659 ÷ 59? (a) 780 (b) 78 (c) 7800
  10. 10.√82 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.0 (d) 9.1
  11. 11.Best estimate of 1844 ÷ 23? (a) 92 (b) 920 (c) 9200
  12. 12.√84 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.0
  13. 13.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.9 (d) 5.8
  14. 14.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.4 (d) 8.1
  15. 15.Best estimate of 1450 ÷ 31? (a) 480 (b) 48 (c) 4800
  16. 16.√24 to 1 decimal place? (a) 4.9 (b) 5.2 (c) 5.1 (d) 5.0
  17. 17.Best estimate of 1461 ÷ 72? (a) 2100 (b) 21 (c) 210
  18. 18.√40 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.5 (d) 6.4
  19. 19.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.7 (d) 5.5
  20. 20.Best estimate of 1477 ÷ 23? (a) 74 (b) 740 (c) 7400
  21. 21.Best estimate of 3276 ÷ 79? (a) 4100 (b) 41 (c) 410
  22. 22.Best estimate of 2425 ÷ 86? (a) 2700 (b) 27 (c) 270
  23. 23.√43 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.7
  24. 24.Best estimate of 2558 ÷ 37? (a) 640 (b) 6400 (c) 64
  25. 25.Best estimate of 2850 ÷ 86? (a) 32 (b) 3200 (c) 320
  26. 26.√79 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.9 (d) 8.8
  27. 27.√62 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.7 (d) 7.6
  28. 28.Best estimate of 1387 ÷ 23? (a) 690 (b) 69 (c) 6900
  29. 29.√92 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  30. 30.Best estimate of 3137 ÷ 41? (a) 7800 (b) 780 (c) 78
  31. 31.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.6 (d) 9.4
  32. 32.Best estimate of 6697 ÷ 74? (a) 960 (b) 96 (c) 9600
  33. 33.Best estimate of 5721 ÷ 84? (a) 720 (b) 72 (c) 7200
  34. 34.√21 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.6 (d) 4.8
  35. 35.√58 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.6 (d) 7.7
  36. 36.Best estimate of 4818 ÷ 59? (a) 8000 (b) 800 (c) 80
  37. 37.√52 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.4
  38. 38.√47 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 7.0
  39. 39.Best estimate of 1752 ÷ 34? (a) 580 (b) 58 (c) 5800
  40. 40.Best estimate of 2084 ÷ 27? (a) 690 (b) 6900 (c) 69

Answer key

  1. 8.8
  2. 5.5
  3. 52
  4. 25
  5. 93
  6. 6.5
  7. 69
  8. 25
  9. 78
  10. 9.1
  11. 92
  12. 9.2
  13. 6.1
  14. 8.3
  15. 48
  16. 4.9
  17. 21
  18. 6.3
  19. 5.8
  20. 74
  21. 41
  22. 27
  23. 6.6
  24. 64
  25. 32
  26. 8.9
  27. 7.9
  28. 69
  29. 9.6
  30. 78
  31. 9.3
  32. 96
  33. 72
  34. 4.6
  35. 7.6
  36. 80
  37. 7.2
  38. 6.9
  39. 58
  40. 69

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