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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 520 · 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 1438 ÷ 58? (a) 2400 (b) 240 (c) 24
  2. 2.Best estimate of 6043 ÷ 82? (a) 7600 (b) 760 (c) 76
  3. 3.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  4. 4.Best estimate of 1110 ÷ 47? (a) 22 (b) 2200 (c) 220
  5. 5.Best estimate of 2148 ÷ 24? (a) 1070 (b) 10700 (c) 107
  6. 6.Best estimate of 670 ÷ 49? (a) 130 (b) 13 (c) 1300
  7. 7.√74 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.3
  8. 8.Best estimate of 2681 ÷ 36? (a) 67 (b) 670 (c) 6700
  9. 9.√70 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.3
  10. 10.√75 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.8 (d) 8.7
  11. 11.Best estimate of 3147 ÷ 71? (a) 450 (b) 4500 (c) 45
  12. 12.Best estimate of 4854 ÷ 59? (a) 81 (b) 8100 (c) 810
  13. 13.Best estimate of 1716 ÷ 24? (a) 860 (b) 8600 (c) 86
  14. 14.Best estimate of 2146 ÷ 59? (a) 3600 (b) 36 (c) 360
  15. 15.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  16. 16.√45 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  17. 17.√71 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.5
  18. 18.Best estimate of 1485 ÷ 46? (a) 3000 (b) 300 (c) 30
  19. 19.Best estimate of 6803 ÷ 77? (a) 850 (b) 8500 (c) 85
  20. 20.√35 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.9 (d) 5.7
  21. 21.Best estimate of 4607 ÷ 48? (a) 92 (b) 9200 (c) 920
  22. 22.√52 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.5 (d) 7.3
  23. 23.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  24. 24.Best estimate of 3481 ÷ 76? (a) 4400 (b) 440 (c) 44
  25. 25.Best estimate of 2669 ÷ 42? (a) 6700 (b) 670 (c) 67
  26. 26.√59 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.8 (d) 7.6
  27. 27.√79 to 1 decimal place? (a) 8.8 (b) 9.1 (c) 9.0 (d) 8.9
  28. 28.√56 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.6 (d) 7.7
  29. 29.Best estimate of 4249 ÷ 47? (a) 85 (b) 8500 (c) 850
  30. 30.Best estimate of 5948 ÷ 86? (a) 660 (b) 66 (c) 6600
  31. 31.√83 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 9.3
  32. 32.Best estimate of 4328 ÷ 88? (a) 4800 (b) 48 (c) 480
  33. 33.√21 to 1 decimal place? (a) 4.4 (b) 4.6 (c) 4.3 (d) 4.5
  34. 34.Best estimate of 979 ÷ 33? (a) 330 (b) 3300 (c) 33
  35. 35.√92 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  36. 36.√87 to 1 decimal place? (a) 9.3 (b) 9.0 (c) 9.2 (d) 9.1
  37. 37.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.3
  38. 38.Best estimate of 2004 ÷ 46? (a) 40 (b) 400 (c) 4000
  39. 39.√48 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 7.2 (d) 7.0
  40. 40.Best estimate of 806 ÷ 42? (a) 20 (b) 200 (c) 2000

Answer key

  1. 24
  2. 76
  3. 8.1
  4. 22
  5. 107
  6. 13
  7. 8.6
  8. 67
  9. 8.4
  10. 8.7
  11. 45
  12. 81
  13. 86
  14. 36
  15. 9.1
  16. 6.7
  17. 8.4
  18. 30
  19. 85
  20. 5.9
  21. 92
  22. 7.2
  23. 9.8
  24. 44
  25. 67
  26. 7.7
  27. 8.9
  28. 7.5
  29. 85
  30. 66
  31. 9.1
  32. 48
  33. 4.6
  34. 33
  35. 9.6
  36. 9.3
  37. 7.4
  38. 40
  39. 6.9
  40. 20

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