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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 541 · 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.√53 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.0 (d) 7.1
  2. 2.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 5.7
  3. 3.Best estimate of 2460 ÷ 32? (a) 8200 (b) 820 (c) 82
  4. 4.√26 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.1 (d) 5.3
  5. 5.√46 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 6.8
  6. 6.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.2 (d) 8.1
  7. 7.√41 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.4 (d) 6.6
  8. 8.Best estimate of 6497 ÷ 88? (a) 7200 (b) 720 (c) 72
  9. 9.Best estimate of 1482 ÷ 26? (a) 490 (b) 4900 (c) 49
  10. 10.Best estimate of 3468 ÷ 59? (a) 580 (b) 5800 (c) 58
  11. 11.Best estimate of 2182 ÷ 56? (a) 3600 (b) 360 (c) 36
  12. 12.√79 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.6 (d) 8.7
  13. 13.Best estimate of 6452 ÷ 74? (a) 92 (b) 9200 (c) 920
  14. 14.Best estimate of 5698 ÷ 67? (a) 81 (b) 810 (c) 8100
  15. 15.√80 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 8.8
  16. 16.Best estimate of 2474 ÷ 54? (a) 4900 (b) 49 (c) 490
  17. 17.Best estimate of 5235 ÷ 86? (a) 580 (b) 5800 (c) 58
  18. 18.√88 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.1
  19. 19.Best estimate of 2228 ÷ 46? (a) 450 (b) 4500 (c) 45
  20. 20.√28 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.1 (d) 5.3
  21. 21.Best estimate of 3278 ÷ 41? (a) 820 (b) 82 (c) 8200
  22. 22.Best estimate of 1199 ÷ 44? (a) 3000 (b) 300 (c) 30
  23. 23.√59 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.7 (d) 7.8
  24. 24.Best estimate of 820 ÷ 23? (a) 410 (b) 41 (c) 4100
  25. 25.Best estimate of 5462 ÷ 86? (a) 61 (b) 6100 (c) 610
  26. 26.Best estimate of 1596 ÷ 26? (a) 53 (b) 530 (c) 5300
  27. 27.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.7 (d) 9.9
  28. 28.Best estimate of 5125 ÷ 58? (a) 8500 (b) 85 (c) 850
  29. 29.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 6.2
  30. 30.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  31. 31.√90 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.8 (d) 9.6
  32. 32.Best estimate of 1520 ÷ 53? (a) 300 (b) 30 (c) 3000
  33. 33.√22 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.6 (d) 4.8
  34. 34.√40 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.1 (d) 6.2
  35. 35.Best estimate of 5340 ÷ 63? (a) 890 (b) 8900 (c) 89
  36. 36.Best estimate of 2556 ÷ 41? (a) 640 (b) 64 (c) 6400
  37. 37.√29 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.3 (d) 5.2
  38. 38.Best estimate of 5191 ÷ 86? (a) 5800 (b) 58 (c) 580
  39. 39.Best estimate of 3587 ÷ 83? (a) 4500 (b) 45 (c) 450
  40. 40.Best estimate of 5858 ÷ 68? (a) 840 (b) 8400 (c) 84

Answer key

  1. 7.3
  2. 5.8
  3. 82
  4. 5.1
  5. 6.8
  6. 8.1
  7. 6.4
  8. 72
  9. 49
  10. 58
  11. 36
  12. 8.9
  13. 92
  14. 81
  15. 8.9
  16. 49
  17. 58
  18. 9.4
  19. 45
  20. 5.3
  21. 82
  22. 30
  23. 7.7
  24. 41
  25. 61
  26. 53
  27. 9.9
  28. 85
  29. 6.1
  30. 7.4
  31. 9.5
  32. 30
  33. 4.7
  34. 6.3
  35. 89
  36. 64
  37. 5.4
  38. 58
  39. 45
  40. 84

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