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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 721 · 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.Best estimate of 3317 ÷ 36? (a) 8300 (b) 830 (c) 83
  2. 2.√59 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 7.6
  3. 3.√41 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.2 (d) 6.4
  4. 4.√46 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.6 (d) 6.7
  5. 5.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  6. 6.Best estimate of 1214 ÷ 61? (a) 20 (b) 200 (c) 2000
  7. 7.√75 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.8
  8. 8.√26 to 1 decimal place? (a) 5.3 (b) 5.0 (c) 5.2 (d) 5.1
  9. 9.√72 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.2 (d) 8.3
  10. 10.Best estimate of 2301 ÷ 31? (a) 7700 (b) 770 (c) 77
  11. 11.Best estimate of 1106 ÷ 41? (a) 28 (b) 2800 (c) 280
  12. 12.Best estimate of 3406 ÷ 48? (a) 680 (b) 6800 (c) 68
  13. 13.Best estimate of 3986 ÷ 43? (a) 10000 (b) 1000 (c) 100
  14. 14.√55 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.4
  15. 15.Best estimate of 3215 ÷ 46? (a) 6400 (b) 640 (c) 64
  16. 16.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.7 (d) 5.9
  17. 17.√31 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.3
  18. 18.Best estimate of 772 ÷ 42? (a) 19 (b) 190 (c) 1900
  19. 19.Best estimate of 4140 ÷ 77? (a) 5200 (b) 520 (c) 52
  20. 20.√76 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.4
  21. 21.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.2 (d) 8.1
  22. 22.√21 to 1 decimal place? (a) 4.4 (b) 4.3 (c) 4.6 (d) 4.5
  23. 23.Best estimate of 1098 ÷ 88? (a) 120 (b) 1200 (c) 12
  24. 24.√85 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.0 (d) 9.1
  25. 25.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.5 (d) 9.7
  26. 26.√29 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.2 (d) 5.5
  27. 27.Best estimate of 5702 ÷ 67? (a) 8100 (b) 810 (c) 81
  28. 28.Best estimate of 5252 ÷ 89? (a) 5800 (b) 58 (c) 580
  29. 29.Best estimate of 1093 ÷ 88? (a) 1200 (b) 12 (c) 120
  30. 30.√48 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.7 (d) 6.8
  31. 31.√38 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.0 (d) 6.1
  32. 32.Best estimate of 856 ÷ 22? (a) 43 (b) 430 (c) 4300
  33. 33.Best estimate of 3527 ÷ 76? (a) 440 (b) 4400 (c) 44
  34. 34.√44 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  35. 35.√53 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.0
  36. 36.Best estimate of 3038 ÷ 32? (a) 101 (b) 10100 (c) 1010
  37. 37.Best estimate of 3574 ÷ 48? (a) 710 (b) 71 (c) 7100
  38. 38.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.6 (d) 9.9
  39. 39.√43 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.7 (d) 6.5
  40. 40.Best estimate of 6419 ÷ 86? (a) 710 (b) 7100 (c) 71

Answer key

  1. 83
  2. 7.7
  3. 6.4
  4. 6.8
  5. 9.1
  6. 20
  7. 8.7
  8. 5.1
  9. 8.5
  10. 77
  11. 28
  12. 68
  13. 100
  14. 7.4
  15. 64
  16. 5.8
  17. 5.6
  18. 19
  19. 52
  20. 8.7
  21. 8.1
  22. 4.6
  23. 12
  24. 9.2
  25. 9.6
  26. 5.4
  27. 81
  28. 58
  29. 12
  30. 6.9
  31. 6.2
  32. 43
  33. 44
  34. 6.6
  35. 7.3
  36. 101
  37. 71
  38. 9.7
  39. 6.6
  40. 71

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