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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 741 · 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.√84 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.2
  2. 2.Best estimate of 1723 ÷ 43? (a) 430 (b) 43 (c) 4300
  3. 3.Best estimate of 3448 ÷ 59? (a) 570 (b) 5700 (c) 57
  4. 4.Best estimate of 3926 ÷ 79? (a) 4900 (b) 49 (c) 490
  5. 5.Best estimate of 2318 ÷ 71? (a) 330 (b) 3300 (c) 33
  6. 6.Best estimate of 5235 ÷ 66? (a) 75 (b) 7500 (c) 750
  7. 7.√50 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.1 (d) 7.0
  8. 8.Best estimate of 2879 ÷ 84? (a) 360 (b) 36 (c) 3600
  9. 9.√67 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.5
  10. 10.Best estimate of 3686 ÷ 51? (a) 7400 (b) 74 (c) 740
  11. 11.Best estimate of 5009 ÷ 86? (a) 560 (b) 5600 (c) 56
  12. 12.Best estimate of 1052 ÷ 59? (a) 18 (b) 180 (c) 1800
  13. 13.Best estimate of 2519 ÷ 34? (a) 840 (b) 8400 (c) 84
  14. 14.Best estimate of 2494 ÷ 68? (a) 360 (b) 3600 (c) 36
  15. 15.√65 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.0 (d) 8.2
  16. 16.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.3 (d) 7.4
  17. 17.Best estimate of 923 ÷ 36? (a) 2300 (b) 230 (c) 23
  18. 18.Best estimate of 3070 ÷ 69? (a) 44 (b) 440 (c) 4400
  19. 19.Best estimate of 1620 ÷ 62? (a) 270 (b) 2700 (c) 27
  20. 20.Best estimate of 5627 ÷ 68? (a) 800 (b) 8000 (c) 80
  21. 21.Best estimate of 8111 ÷ 87? (a) 90 (b) 9000 (c) 900
  22. 22.Best estimate of 3510 ÷ 82? (a) 440 (b) 44 (c) 4400
  23. 23.√72 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  24. 24.Best estimate of 3880 ÷ 81? (a) 4900 (b) 49 (c) 490
  25. 25.Best estimate of 1594 ÷ 54? (a) 320 (b) 3200 (c) 32
  26. 26.Best estimate of 4610 ÷ 77? (a) 58 (b) 580 (c) 5800
  27. 27.Best estimate of 3121 ÷ 67? (a) 450 (b) 45 (c) 4500
  28. 28.Best estimate of 1582 ÷ 69? (a) 2300 (b) 23 (c) 230
  29. 29.√47 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 6.9
  30. 30.√43 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.3
  31. 31.Best estimate of 902 ÷ 42? (a) 2300 (b) 230 (c) 23
  32. 32.Best estimate of 1697 ÷ 29? (a) 570 (b) 57 (c) 5700
  33. 33.Best estimate of 4982 ÷ 72? (a) 7100 (b) 710 (c) 71
  34. 34.√98 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  35. 35.Best estimate of 5850 ÷ 74? (a) 84 (b) 8400 (c) 840
  36. 36.√37 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 6.1
  37. 37.Best estimate of 1083 ÷ 41? (a) 2700 (b) 27 (c) 270
  38. 38.Best estimate of 1606 ÷ 46? (a) 320 (b) 32 (c) 3200
  39. 39.√62 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  40. 40.Best estimate of 7107 ÷ 86? (a) 79 (b) 790 (c) 7900

Answer key

  1. 9.2
  2. 43
  3. 57
  4. 49
  5. 33
  6. 75
  7. 7.1
  8. 36
  9. 8.2
  10. 74
  11. 56
  12. 18
  13. 84
  14. 36
  15. 8.1
  16. 7.6
  17. 23
  18. 44
  19. 27
  20. 80
  21. 90
  22. 44
  23. 8.5
  24. 49
  25. 32
  26. 58
  27. 45
  28. 23
  29. 6.9
  30. 6.6
  31. 23
  32. 57
  33. 71
  34. 9.9
  35. 84
  36. 6.1
  37. 27
  38. 32
  39. 7.9
  40. 79

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