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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 873 · 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 4731 ÷ 64? (a) 7900 (b) 790 (c) 79
  2. 2.√44 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.6
  3. 3.Best estimate of 2103 ÷ 77? (a) 26 (b) 260 (c) 2600
  4. 4.√94 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.9 (d) 9.7
  5. 5.√40 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.3
  6. 6.Best estimate of 3360 ÷ 42? (a) 840 (b) 8400 (c) 84
  7. 7.√20 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.3 (d) 4.6
  8. 8.Best estimate of 2510 ÷ 36? (a) 6300 (b) 63 (c) 630
  9. 9.√90 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.6
  10. 10.√46 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.8
  11. 11.Best estimate of 1019 ÷ 37? (a) 2500 (b) 25 (c) 250
  12. 12.√79 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.7 (d) 8.9
  13. 13.√50 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.4
  14. 14.Best estimate of 1430 ÷ 46? (a) 290 (b) 29 (c) 2900
  15. 15.Best estimate of 2924 ÷ 62? (a) 49 (b) 490 (c) 4900
  16. 16.Best estimate of 1464 ÷ 23? (a) 730 (b) 7300 (c) 73
  17. 17.Best estimate of 1454 ÷ 39? (a) 36 (b) 360 (c) 3600
  18. 18.Best estimate of 777 ÷ 52? (a) 16 (b) 1600 (c) 160
  19. 19.√23 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  20. 20.√37 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.0
  21. 21.√59 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.8
  22. 22.√98 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 9.9 (d) 10.0
  23. 23.√26 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.1 (d) 5.0
  24. 24.Best estimate of 2239 ÷ 26? (a) 750 (b) 75 (c) 7500
  25. 25.Best estimate of 6154 ÷ 73? (a) 880 (b) 8800 (c) 88
  26. 26.Best estimate of 1930 ÷ 32? (a) 6400 (b) 64 (c) 640
  27. 27.Best estimate of 6146 ÷ 73? (a) 8800 (b) 88 (c) 880
  28. 28.Best estimate of 889 ÷ 52? (a) 180 (b) 18 (c) 1800
  29. 29.√87 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.5
  30. 30.Best estimate of 1150 ÷ 34? (a) 38 (b) 3800 (c) 380
  31. 31.Best estimate of 921 ÷ 43? (a) 23 (b) 2300 (c) 230
  32. 32.√92 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.3 (d) 9.5
  33. 33.Best estimate of 6023 ÷ 66? (a) 86 (b) 8600 (c) 860
  34. 34.√45 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.9 (d) 6.8
  35. 35.√22 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  36. 36.√78 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  37. 37.Best estimate of 2950 ÷ 46? (a) 5900 (b) 59 (c) 590
  38. 38.Best estimate of 4782 ÷ 54? (a) 96 (b) 960 (c) 9600
  39. 39.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.4
  40. 40.√70 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.3

Answer key

  1. 79
  2. 6.6
  3. 26
  4. 9.7
  5. 6.3
  6. 84
  7. 4.5
  8. 63
  9. 9.5
  10. 6.8
  11. 25
  12. 8.9
  13. 7.1
  14. 29
  15. 49
  16. 73
  17. 36
  18. 16
  19. 4.8
  20. 6.1
  21. 7.7
  22. 9.9
  23. 5.1
  24. 75
  25. 88
  26. 64
  27. 88
  28. 18
  29. 9.3
  30. 38
  31. 23
  32. 9.6
  33. 86
  34. 6.7
  35. 4.7
  36. 8.8
  37. 59
  38. 96
  39. 7.1
  40. 8.4

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