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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 784 · 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 1961 ÷ 26? (a) 650 (b) 6500 (c) 65
  2. 2.√29 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.6 (d) 5.4
  3. 3.√61 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.9 (d) 8.1
  4. 4.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  5. 5.Best estimate of 1894 ÷ 31? (a) 63 (b) 6300 (c) 630
  6. 6.Best estimate of 2058 ÷ 26? (a) 690 (b) 6900 (c) 69
  7. 7.Best estimate of 2303 ÷ 43? (a) 580 (b) 58 (c) 5800
  8. 8.Best estimate of 2353 ÷ 47? (a) 47 (b) 470 (c) 4700
  9. 9.Best estimate of 1839 ÷ 76? (a) 23 (b) 2300 (c) 230
  10. 10.√51 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 6.9 (d) 7.0
  11. 11.√77 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 9.1
  12. 12.√69 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.1 (d) 8.3
  13. 13.√32 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.5 (d) 5.6
  14. 14.Best estimate of 2243 ÷ 27? (a) 7500 (b) 75 (c) 750
  15. 15.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  16. 16.√87 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  17. 17.Best estimate of 5728 ÷ 77? (a) 7200 (b) 720 (c) 72
  18. 18.Best estimate of 1626 ÷ 51? (a) 330 (b) 33 (c) 3300
  19. 19.√24 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 5.1 (d) 4.9
  20. 20.Best estimate of 4029 ÷ 62? (a) 670 (b) 67 (c) 6700
  21. 21.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.3
  22. 22.√94 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 9.7
  23. 23.Best estimate of 1224 ÷ 32? (a) 4100 (b) 410 (c) 41
  24. 24.Best estimate of 1377 ÷ 49? (a) 2800 (b) 280 (c) 28
  25. 25.√26 to 1 decimal place? (a) 5.4 (b) 5.1 (c) 5.2 (d) 5.3
  26. 26.Best estimate of 1430 ÷ 26? (a) 480 (b) 48 (c) 4800
  27. 27.Best estimate of 1502 ÷ 76? (a) 190 (b) 1900 (c) 19
  28. 28.Best estimate of 2099 ÷ 33? (a) 700 (b) 70 (c) 7000
  29. 29.Best estimate of 5694 ÷ 71? (a) 810 (b) 8100 (c) 81
  30. 30.√72 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.4 (d) 8.5
  31. 31.√67 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 8.2
  32. 32.Best estimate of 2701 ÷ 42? (a) 680 (b) 6800 (c) 68
  33. 33.Best estimate of 1714 ÷ 42? (a) 430 (b) 4300 (c) 43
  34. 34.Best estimate of 1118 ÷ 56? (a) 19 (b) 1900 (c) 190
  35. 35.Best estimate of 629 ÷ 26? (a) 2100 (b) 21 (c) 210
  36. 36.Best estimate of 2017 ÷ 31? (a) 67 (b) 670 (c) 6700
  37. 37.Best estimate of 1214 ÷ 24? (a) 61 (b) 610 (c) 6100
  38. 38.√50 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.2 (d) 7.3
  39. 39.Best estimate of 1817 ÷ 62? (a) 300 (b) 3000 (c) 30
  40. 40.Best estimate of 3981 ÷ 43? (a) 1000 (b) 10000 (c) 100

Answer key

  1. 65
  2. 5.4
  3. 7.8
  4. 7.6
  5. 63
  6. 69
  7. 58
  8. 47
  9. 23
  10. 7.1
  11. 8.8
  12. 8.3
  13. 5.7
  14. 75
  15. 6.1
  16. 9.3
  17. 72
  18. 33
  19. 4.9
  20. 67
  21. 8.6
  22. 9.7
  23. 41
  24. 28
  25. 5.1
  26. 48
  27. 19
  28. 70
  29. 81
  30. 8.5
  31. 8.2
  32. 68
  33. 43
  34. 19
  35. 21
  36. 67
  37. 61
  38. 7.1
  39. 30
  40. 100

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