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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 963 · 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.√51 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.1 (d) 7.2
  2. 2.Best estimate of 2440 ÷ 29? (a) 810 (b) 8100 (c) 81
  3. 3.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.8 (d) 9.1
  4. 4.√52 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.4
  5. 5.Best estimate of 2702 ÷ 36? (a) 680 (b) 6800 (c) 68
  6. 6.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 7.6
  7. 7.Best estimate of 4809 ÷ 56? (a) 8000 (b) 800 (c) 80
  8. 8.Best estimate of 5832 ÷ 62? (a) 970 (b) 97 (c) 9700
  9. 9.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  10. 10.√72 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.7
  11. 11.√94 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.7
  12. 12.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.5
  13. 13.√59 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 7.7
  14. 14.√69 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.1 (d) 8.3
  15. 15.√32 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.6 (d) 5.8
  16. 16.Best estimate of 794 ÷ 36? (a) 20 (b) 2000 (c) 200
  17. 17.√66 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 8.3
  18. 18.Best estimate of 1435 ÷ 24? (a) 720 (b) 7200 (c) 72
  19. 19.√26 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.1 (d) 5.3
  20. 20.√62 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 8.0
  21. 21.√55 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  22. 22.Best estimate of 4084 ÷ 69? (a) 580 (b) 5800 (c) 58
  23. 23.√37 to 1 decimal place? (a) 5.9 (b) 6.2 (c) 6.1 (d) 6.0
  24. 24.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.8
  25. 25.√40 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.0 (d) 6.2
  26. 26.Best estimate of 2008 ÷ 32? (a) 670 (b) 67 (c) 6700
  27. 27.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.4 (d) 5.1
  28. 28.Best estimate of 2495 ÷ 62? (a) 420 (b) 4200 (c) 42
  29. 29.Best estimate of 311 ÷ 24? (a) 1600 (b) 16 (c) 160
  30. 30.Best estimate of 3619 ÷ 62? (a) 60 (b) 600 (c) 6000
  31. 31.Best estimate of 3290 ÷ 52? (a) 6600 (b) 660 (c) 66
  32. 32.√27 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.4
  33. 33.Best estimate of 1438 ÷ 44? (a) 36 (b) 3600 (c) 360
  34. 34.Best estimate of 1924 ÷ 21? (a) 960 (b) 9600 (c) 96
  35. 35.Best estimate of 3224 ÷ 38? (a) 81 (b) 810 (c) 8100
  36. 36.Best estimate of 4360 ÷ 46? (a) 870 (b) 8700 (c) 87
  37. 37.√92 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  38. 38.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 9.2
  39. 39.Best estimate of 329 ÷ 27? (a) 1100 (b) 11 (c) 110
  40. 40.Best estimate of 2982 ÷ 37? (a) 7500 (b) 750 (c) 75

Answer key

  1. 7.1
  2. 81
  3. 8.9
  4. 7.2
  5. 68
  6. 7.8
  7. 80
  8. 97
  9. 7.6
  10. 8.5
  11. 9.7
  12. 9.8
  13. 7.7
  14. 8.3
  15. 5.7
  16. 20
  17. 8.1
  18. 72
  19. 5.1
  20. 7.9
  21. 7.4
  22. 58
  23. 6.1
  24. 9.5
  25. 6.3
  26. 67
  27. 5.3
  28. 42
  29. 16
  30. 60
  31. 66
  32. 5.2
  33. 36
  34. 96
  35. 81
  36. 87
  37. 9.6
  38. 8.9
  39. 11
  40. 75

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