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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 482 · 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.√96 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.7 (d) 9.8
  2. 2.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.8 (d) 4.9
  3. 3.√61 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 7.7
  4. 4.Best estimate of 2338 ÷ 34? (a) 780 (b) 7800 (c) 78
  5. 5.√32 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.0 (d) 5.7
  6. 6.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.5 (d) 5.6
  7. 7.Best estimate of 4955 ÷ 72? (a) 71 (b) 710 (c) 7100
  8. 8.Best estimate of 5229 ÷ 76? (a) 6500 (b) 65 (c) 650
  9. 9.Best estimate of 6592 ÷ 77? (a) 8200 (b) 820 (c) 82
  10. 10.√20 to 1 decimal place? (a) 4.4 (b) 4.5 (c) 4.6 (d) 4.3
  11. 11.Best estimate of 1184 ÷ 81? (a) 1500 (b) 15 (c) 150
  12. 12.Best estimate of 469 ÷ 32? (a) 16 (b) 160 (c) 1600
  13. 13.Best estimate of 7643 ÷ 81? (a) 96 (b) 960 (c) 9600
  14. 14.Best estimate of 3379 ÷ 36? (a) 840 (b) 8400 (c) 84
  15. 15.Best estimate of 6938 ÷ 76? (a) 87 (b) 870 (c) 8700
  16. 16.Best estimate of 728 ÷ 23? (a) 36 (b) 3600 (c) 360
  17. 17.Best estimate of 5246 ÷ 66? (a) 75 (b) 750 (c) 7500
  18. 18.Best estimate of 2609 ÷ 72? (a) 3700 (b) 370 (c) 37
  19. 19.Best estimate of 1294 ÷ 76? (a) 16 (b) 160 (c) 1600
  20. 20.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.9
  21. 21.Best estimate of 945 ÷ 26? (a) 3200 (b) 32 (c) 320
  22. 22.√75 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.5 (d) 8.7
  23. 23.Best estimate of 538 ÷ 28? (a) 1800 (b) 18 (c) 180
  24. 24.Best estimate of 5748 ÷ 67? (a) 82 (b) 8200 (c) 820
  25. 25.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.4
  26. 26.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  27. 27.√48 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 6.8 (d) 7.0
  28. 28.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.2 (d) 8.4
  29. 29.Best estimate of 1870 ÷ 36? (a) 470 (b) 47 (c) 4700
  30. 30.Best estimate of 1809 ÷ 26? (a) 60 (b) 6000 (c) 600
  31. 31.Best estimate of 4169 ÷ 62? (a) 6900 (b) 690 (c) 69
  32. 32.Best estimate of 514 ÷ 27? (a) 170 (b) 1700 (c) 17
  33. 33.√28 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.4 (d) 5.2
  34. 34.√98 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.7 (d) 9.8
  35. 35.√80 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 8.9 (d) 9.0
  36. 36.Best estimate of 3475 ÷ 39? (a) 87 (b) 8700 (c) 870
  37. 37.Best estimate of 3726 ÷ 49? (a) 7500 (b) 75 (c) 750
  38. 38.√74 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.6
  39. 39.Best estimate of 2344 ÷ 37? (a) 5900 (b) 590 (c) 59
  40. 40.Best estimate of 2792 ÷ 78? (a) 3500 (b) 350 (c) 35

Answer key

  1. 9.8
  2. 5.1
  3. 7.8
  4. 78
  5. 5.7
  6. 5.8
  7. 71
  8. 65
  9. 82
  10. 4.5
  11. 15
  12. 16
  13. 96
  14. 84
  15. 87
  16. 36
  17. 75
  18. 37
  19. 16
  20. 9.6
  21. 32
  22. 8.7
  23. 18
  24. 82
  25. 7.4
  26. 7.6
  27. 6.9
  28. 8.3
  29. 47
  30. 60
  31. 69
  32. 17
  33. 5.3
  34. 9.9
  35. 8.9
  36. 87
  37. 75
  38. 8.6
  39. 59
  40. 35

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