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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 638 · 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.√82 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.3 (d) 9.2
  2. 2.Best estimate of 2152 ÷ 56? (a) 360 (b) 3600 (c) 36
  3. 3.Best estimate of 5930 ÷ 89? (a) 660 (b) 6600 (c) 66
  4. 4.Best estimate of 1172 ÷ 58? (a) 20 (b) 2000 (c) 200
  5. 5.Best estimate of 1064 ÷ 32? (a) 3500 (b) 350 (c) 35
  6. 6.√51 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.0
  7. 7.Best estimate of 2208 ÷ 82? (a) 280 (b) 2800 (c) 28
  8. 8.√43 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.6 (d) 6.5
  9. 9.Best estimate of 6914 ÷ 73? (a) 9900 (b) 990 (c) 99
  10. 10.√21 to 1 decimal place? (a) 4.6 (b) 4.3 (c) 4.5 (d) 4.4
  11. 11.Best estimate of 1987 ÷ 46? (a) 400 (b) 40 (c) 4000
  12. 12.√74 to 1 decimal place? (a) 8.6 (b) 8.3 (c) 8.5 (d) 8.4
  13. 13.√28 to 1 decimal place? (a) 5.3 (b) 5.6 (c) 5.4 (d) 5.5
  14. 14.√24 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 4.8
  15. 15.Best estimate of 817 ÷ 26? (a) 2700 (b) 270 (c) 27
  16. 16.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.7
  17. 17.Best estimate of 3239 ÷ 39? (a) 81 (b) 8100 (c) 810
  18. 18.√41 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.3 (d) 6.4
  19. 19.Best estimate of 3185 ÷ 56? (a) 5300 (b) 530 (c) 53
  20. 20.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.2
  21. 21.Best estimate of 4232 ÷ 47? (a) 8500 (b) 850 (c) 85
  22. 22.√96 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 9.8 (d) 10.0
  23. 23.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  24. 24.Best estimate of 3048 ÷ 66? (a) 440 (b) 44 (c) 4400
  25. 25.√92 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  26. 26.Best estimate of 6594 ÷ 73? (a) 94 (b) 9400 (c) 940
  27. 27.Best estimate of 301 ÷ 24? (a) 150 (b) 15 (c) 1500
  28. 28.√65 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  29. 29.√76 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.8 (d) 8.6
  30. 30.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  31. 31.Best estimate of 873 ÷ 47? (a) 1700 (b) 170 (c) 17
  32. 32.Best estimate of 1299 ÷ 22? (a) 650 (b) 6500 (c) 65
  33. 33.√32 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 6.0
  34. 34.Best estimate of 2177 ÷ 33? (a) 73 (b) 730 (c) 7300
  35. 35.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 6.9
  36. 36.√37 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 6.1
  37. 37.Best estimate of 3124 ÷ 54? (a) 62 (b) 620 (c) 6200
  38. 38.Best estimate of 2969 ÷ 51? (a) 5900 (b) 59 (c) 590
  39. 39.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.1
  40. 40.√70 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4

Answer key

  1. 9.1
  2. 36
  3. 66
  4. 20
  5. 35
  6. 7.1
  7. 28
  8. 6.6
  9. 99
  10. 4.6
  11. 40
  12. 8.6
  13. 5.3
  14. 4.9
  15. 27
  16. 7.6
  17. 81
  18. 6.4
  19. 53
  20. 7.4
  21. 85
  22. 9.8
  23. 7.2
  24. 44
  25. 9.6
  26. 94
  27. 15
  28. 8.1
  29. 8.7
  30. 6.2
  31. 17
  32. 65
  33. 5.7
  34. 73
  35. 7.1
  36. 6.1
  37. 62
  38. 59
  39. 9.4
  40. 8.4

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