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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 353 · 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.√75 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  2. 2.√86 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.0
  3. 3.Best estimate of 1088 ÷ 47? (a) 220 (b) 22 (c) 2200
  4. 4.Best estimate of 1593 ÷ 34? (a) 53 (b) 5300 (c) 530
  5. 5.√40 to 1 decimal place? (a) 6.2 (b) 6.5 (c) 6.4 (d) 6.3
  6. 6.Best estimate of 1405 ÷ 46? (a) 2800 (b) 28 (c) 280
  7. 7.Best estimate of 3163 ÷ 43? (a) 7900 (b) 790 (c) 79
  8. 8.Best estimate of 4090 ÷ 43? (a) 10200 (b) 1020 (c) 102
  9. 9.Best estimate of 2349 ÷ 42? (a) 5900 (b) 590 (c) 59
  10. 10.√55 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.6
  11. 11.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  12. 12.Best estimate of 2058 ÷ 79? (a) 2600 (b) 260 (c) 26
  13. 13.√89 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.1 (d) 9.3
  14. 14.√30 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.8 (d) 5.6
  15. 15.Best estimate of 6892 ÷ 81? (a) 86 (b) 8600 (c) 860
  16. 16.Best estimate of 2602 ÷ 34? (a) 8700 (b) 870 (c) 87
  17. 17.Best estimate of 1629 ÷ 62? (a) 2700 (b) 270 (c) 27
  18. 18.Best estimate of 3738 ÷ 56? (a) 6200 (b) 62 (c) 620
  19. 19.Best estimate of 6630 ÷ 88? (a) 740 (b) 74 (c) 7400
  20. 20.√23 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.8 (d) 4.6
  21. 21.√92 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.6 (d) 9.4
  22. 22.√78 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.1 (d) 9.0
  23. 23.√85 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 9.2
  24. 24.Best estimate of 4450 ÷ 67? (a) 6400 (b) 64 (c) 640
  25. 25.Best estimate of 3621 ÷ 61? (a) 600 (b) 60 (c) 6000
  26. 26.Best estimate of 1276 ÷ 26? (a) 430 (b) 4300 (c) 43
  27. 27.√61 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  28. 28.√20 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.6 (d) 4.8
  29. 29.Best estimate of 1765 ÷ 46? (a) 350 (b) 35 (c) 3500
  30. 30.Best estimate of 2843 ÷ 59? (a) 470 (b) 47 (c) 4700
  31. 31.√44 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.5
  32. 32.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.4 (d) 8.2
  33. 33.Best estimate of 2142 ÷ 38? (a) 540 (b) 54 (c) 5400
  34. 34.Best estimate of 5876 ÷ 72? (a) 840 (b) 8400 (c) 84
  35. 35.Best estimate of 1923 ÷ 21? (a) 9600 (b) 960 (c) 96
  36. 36.√88 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.4
  37. 37.Best estimate of 4727 ÷ 56? (a) 79 (b) 790 (c) 7900
  38. 38.√65 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.1
  39. 39.√24 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.1 (d) 5.0
  40. 40.√94 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.7 (d) 9.9

Answer key

  1. 8.7
  2. 9.3
  3. 22
  4. 53
  5. 6.3
  6. 28
  7. 79
  8. 102
  9. 59
  10. 7.4
  11. 9.3
  12. 26
  13. 9.4
  14. 5.5
  15. 86
  16. 87
  17. 27
  18. 62
  19. 74
  20. 4.8
  21. 9.6
  22. 8.8
  23. 9.2
  24. 64
  25. 60
  26. 43
  27. 7.8
  28. 4.5
  29. 35
  30. 47
  31. 6.6
  32. 8.3
  33. 54
  34. 84
  35. 96
  36. 9.4
  37. 79
  38. 8.1
  39. 4.9
  40. 9.7

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