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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 691 · 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.√76 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 8.7
  2. 2.√31 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4
  3. 3.Best estimate of 2779 ÷ 52? (a) 56 (b) 560 (c) 5600
  4. 4.√23 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.6 (d) 4.8
  5. 5.√74 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.8 (d) 8.6
  6. 6.Best estimate of 2660 ÷ 32? (a) 890 (b) 8900 (c) 89
  7. 7.√24 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  8. 8.√69 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  9. 9.√88 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.2 (d) 9.3
  10. 10.Best estimate of 2346 ÷ 67? (a) 3400 (b) 34 (c) 340
  11. 11.Best estimate of 6184 ÷ 79? (a) 770 (b) 7700 (c) 77
  12. 12.√67 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  13. 13.Best estimate of 4201 ÷ 51? (a) 840 (b) 84 (c) 8400
  14. 14.Best estimate of 1095 ÷ 36? (a) 27 (b) 270 (c) 2700
  15. 15.Best estimate of 899 ÷ 32? (a) 30 (b) 3000 (c) 300
  16. 16.Best estimate of 1485 ÷ 23? (a) 740 (b) 7400 (c) 74
  17. 17.Best estimate of 1581 ÷ 62? (a) 260 (b) 26 (c) 2600
  18. 18.Best estimate of 844 ÷ 27? (a) 280 (b) 28 (c) 2800
  19. 19.√21 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.3 (d) 4.4
  20. 20.Best estimate of 1029 ÷ 41? (a) 2600 (b) 26 (c) 260
  21. 21.Best estimate of 3892 ÷ 48? (a) 780 (b) 78 (c) 7800
  22. 22.√40 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.3 (d) 6.2
  23. 23.Best estimate of 1318 ÷ 21? (a) 660 (b) 66 (c) 6600
  24. 24.Best estimate of 401 ÷ 26? (a) 130 (b) 13 (c) 1300
  25. 25.√65 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.4 (d) 8.3
  26. 26.Best estimate of 2164 ÷ 23? (a) 108 (b) 10800 (c) 1080
  27. 27.Best estimate of 4056 ÷ 52? (a) 810 (b) 8100 (c) 81
  28. 28.√37 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 6.2
  29. 29.Best estimate of 3119 ÷ 66? (a) 45 (b) 450 (c) 4500
  30. 30.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 5.2
  31. 31.Best estimate of 1615 ÷ 23? (a) 810 (b) 8100 (c) 81
  32. 32.√27 to 1 decimal place? (a) 5.4 (b) 5.1 (c) 5.2 (d) 5.3
  33. 33.Best estimate of 5637 ÷ 84? (a) 700 (b) 7000 (c) 70
  34. 34.Best estimate of 376 ÷ 24? (a) 19 (b) 190 (c) 1900
  35. 35.√61 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 8.0
  36. 36.√59 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.7 (d) 7.5
  37. 37.Best estimate of 948 ÷ 33? (a) 3200 (b) 32 (c) 320
  38. 38.√43 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.5 (d) 6.6
  39. 39.Best estimate of 937 ÷ 39? (a) 2300 (b) 23 (c) 230
  40. 40.Best estimate of 4782 ÷ 81? (a) 6000 (b) 60 (c) 600

Answer key

  1. 8.7
  2. 5.6
  3. 56
  4. 4.8
  5. 8.6
  6. 89
  7. 4.9
  8. 8.3
  9. 9.4
  10. 34
  11. 77
  12. 8.2
  13. 84
  14. 27
  15. 30
  16. 74
  17. 26
  18. 28
  19. 4.6
  20. 26
  21. 78
  22. 6.3
  23. 66
  24. 13
  25. 8.1
  26. 108
  27. 81
  28. 6.1
  29. 45
  30. 5.1
  31. 81
  32. 5.2
  33. 70
  34. 19
  35. 7.8
  36. 7.7
  37. 32
  38. 6.6
  39. 23
  40. 60

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