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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 379 · 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.√79 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 9.0 (d) 8.8
  2. 2.Best estimate of 3428 ÷ 41? (a) 8600 (b) 860 (c) 86
  3. 3.Best estimate of 4060 ÷ 76? (a) 5100 (b) 51 (c) 510
  4. 4.Best estimate of 1901 ÷ 67? (a) 2700 (b) 270 (c) 27
  5. 5.Best estimate of 1187 ÷ 27? (a) 400 (b) 40 (c) 4000
  6. 6.√88 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.7
  7. 7.Best estimate of 6218 ÷ 82? (a) 780 (b) 78 (c) 7800
  8. 8.Best estimate of 5007 ÷ 61? (a) 8300 (b) 83 (c) 830
  9. 9.Best estimate of 6474 ÷ 68? (a) 92 (b) 920 (c) 9200
  10. 10.Best estimate of 2434 ÷ 33? (a) 81 (b) 8100 (c) 810
  11. 11.Best estimate of 2005 ÷ 28? (a) 6700 (b) 67 (c) 670
  12. 12.√26 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.1 (d) 5.2
  13. 13.√43 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  14. 14.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.5
  15. 15.Best estimate of 882 ÷ 41? (a) 2200 (b) 22 (c) 220
  16. 16.Best estimate of 6881 ÷ 81? (a) 86 (b) 8600 (c) 860
  17. 17.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 9.7
  18. 18.√20 to 1 decimal place? (a) 4.5 (b) 4.2 (c) 4.3 (d) 4.4
  19. 19.Best estimate of 3483 ÷ 37? (a) 870 (b) 8700 (c) 87
  20. 20.√53 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.3 (d) 7.2
  21. 21.Best estimate of 474 ÷ 34? (a) 1600 (b) 16 (c) 160
  22. 22.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.8 (d) 6.9
  23. 23.Best estimate of 2614 ÷ 57? (a) 440 (b) 4400 (c) 44
  24. 24.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.7 (d) 8.0
  25. 25.Best estimate of 1426 ÷ 46? (a) 290 (b) 29 (c) 2900
  26. 26.Best estimate of 4710 ÷ 63? (a) 790 (b) 79 (c) 7900
  27. 27.Best estimate of 7196 ÷ 78? (a) 900 (b) 9000 (c) 90
  28. 28.Best estimate of 755 ÷ 37? (a) 19 (b) 190 (c) 1900
  29. 29.√41 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.6
  30. 30.Best estimate of 1006 ÷ 27? (a) 3400 (b) 340 (c) 34
  31. 31.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  32. 32.√21 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.6 (d) 4.4
  33. 33.Best estimate of 1080 ÷ 53? (a) 22 (b) 220 (c) 2200
  34. 34.Best estimate of 544 ÷ 26? (a) 18 (b) 1800 (c) 180
  35. 35.Best estimate of 4261 ÷ 52? (a) 850 (b) 85 (c) 8500
  36. 36.Best estimate of 440 ÷ 32? (a) 150 (b) 1500 (c) 15
  37. 37.√31 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.8
  38. 38.√84 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.2 (d) 9.0
  39. 39.√35 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 6.1
  40. 40.Best estimate of 1700 ÷ 23? (a) 85 (b) 850 (c) 8500

Answer key

  1. 8.9
  2. 86
  3. 51
  4. 27
  5. 40
  6. 9.4
  7. 78
  8. 83
  9. 92
  10. 81
  11. 67
  12. 5.1
  13. 6.6
  14. 9.6
  15. 22
  16. 86
  17. 9.8
  18. 4.5
  19. 87
  20. 7.3
  21. 16
  22. 7.1
  23. 44
  24. 7.8
  25. 29
  26. 79
  27. 90
  28. 19
  29. 6.4
  30. 34
  31. 7.6
  32. 4.6
  33. 22
  34. 18
  35. 85
  36. 15
  37. 5.6
  38. 9.2
  39. 5.9
  40. 85

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