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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 336 · 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 1025 ÷ 54? (a) 210 (b) 2100 (c) 21
  2. 2.Best estimate of 4490 ÷ 82? (a) 56 (b) 5600 (c) 560
  3. 3.√96 to 1 decimal place? (a) 9.8 (b) 10.1 (c) 9.9 (d) 10.0
  4. 4.√22 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.9
  5. 5.Best estimate of 5504 ÷ 66? (a) 79 (b) 790 (c) 7900
  6. 6.√79 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 8.9 (d) 9.0
  7. 7.Best estimate of 1522 ÷ 49? (a) 300 (b) 30 (c) 3000
  8. 8.√71 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.2 (d) 8.3
  9. 9.√40 to 1 decimal place? (a) 6.0 (b) 6.3 (c) 6.2 (d) 6.1
  10. 10.Best estimate of 1382 ÷ 29? (a) 4600 (b) 46 (c) 460
  11. 11.Best estimate of 1923 ÷ 26? (a) 6400 (b) 640 (c) 64
  12. 12.Best estimate of 1483 ÷ 26? (a) 4900 (b) 490 (c) 49
  13. 13.Best estimate of 1198 ÷ 26? (a) 400 (b) 40 (c) 4000
  14. 14.√42 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  15. 15.Best estimate of 837 ÷ 26? (a) 28 (b) 2800 (c) 280
  16. 16.Best estimate of 997 ÷ 73? (a) 14 (b) 140 (c) 1400
  17. 17.Best estimate of 6093 ÷ 76? (a) 760 (b) 7600 (c) 76
  18. 18.Best estimate of 1007 ÷ 24? (a) 50 (b) 500 (c) 5000
  19. 19.√29 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.7
  20. 20.√62 to 1 decimal place? (a) 7.7 (b) 8.0 (c) 7.8 (d) 7.9
  21. 21.√48 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 7.0 (d) 6.9
  22. 22.Best estimate of 1770 ÷ 72? (a) 25 (b) 250 (c) 2500
  23. 23.√82 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0
  24. 24.√85 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.1 (d) 9.0
  25. 25.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.9 (d) 7.8
  26. 26.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.4 (d) 8.2
  27. 27.√30 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.8 (d) 5.6
  28. 28.√76 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  29. 29.Best estimate of 3064 ÷ 46? (a) 610 (b) 6100 (c) 61
  30. 30.Best estimate of 4145 ÷ 56? (a) 690 (b) 69 (c) 6900
  31. 31.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.9
  32. 32.Best estimate of 2121 ÷ 27? (a) 7100 (b) 71 (c) 710
  33. 33.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.4 (d) 9.5
  34. 34.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.8
  35. 35.Best estimate of 2043 ÷ 68? (a) 2900 (b) 290 (c) 29
  36. 36.Best estimate of 3023 ÷ 36? (a) 7600 (b) 76 (c) 760
  37. 37.Best estimate of 2654 ÷ 58? (a) 4400 (b) 440 (c) 44
  38. 38.Best estimate of 4671 ÷ 57? (a) 78 (b) 780 (c) 7800
  39. 39.Best estimate of 2467 ÷ 33? (a) 820 (b) 8200 (c) 82
  40. 40.Best estimate of 5332 ÷ 83? (a) 670 (b) 6700 (c) 67

Answer key

  1. 21
  2. 56
  3. 9.8
  4. 4.7
  5. 79
  6. 8.9
  7. 30
  8. 8.4
  9. 6.3
  10. 46
  11. 64
  12. 49
  13. 40
  14. 6.5
  15. 28
  16. 14
  17. 76
  18. 50
  19. 5.4
  20. 7.9
  21. 6.9
  22. 25
  23. 9.1
  24. 9.2
  25. 7.6
  26. 8.1
  27. 5.5
  28. 8.7
  29. 61
  30. 69
  31. 8.6
  32. 71
  33. 9.6
  34. 9.7
  35. 29
  36. 76
  37. 44
  38. 78
  39. 82
  40. 67

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