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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 764 · 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 5638 ÷ 84? (a) 700 (b) 70 (c) 7000
  2. 2.√23 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.5 (d) 4.6
  3. 3.Best estimate of 2055 ÷ 41? (a) 51 (b) 510 (c) 5100
  4. 4.Best estimate of 887 ÷ 42? (a) 2200 (b) 220 (c) 22
  5. 5.Best estimate of 2265 ÷ 31? (a) 760 (b) 76 (c) 7600
  6. 6.Best estimate of 4209 ÷ 46? (a) 840 (b) 84 (c) 8400
  7. 7.Best estimate of 547 ÷ 21? (a) 270 (b) 2700 (c) 27
  8. 8.√96 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 10.1 (d) 9.9
  9. 9.Best estimate of 7285 ÷ 77? (a) 910 (b) 9100 (c) 91
  10. 10.Best estimate of 4858 ÷ 71? (a) 6900 (b) 690 (c) 69
  11. 11.Best estimate of 1291 ÷ 31? (a) 4300 (b) 430 (c) 43
  12. 12.√61 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 8.0 (d) 7.9
  13. 13.Best estimate of 845 ÷ 26? (a) 280 (b) 28 (c) 2800
  14. 14.Best estimate of 5213 ÷ 59? (a) 8700 (b) 870 (c) 87
  15. 15.Best estimate of 1614 ÷ 44? (a) 4000 (b) 40 (c) 400
  16. 16.Best estimate of 946 ÷ 69? (a) 1400 (b) 140 (c) 14
  17. 17.√46 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.7 (d) 6.6
  18. 18.Best estimate of 5121 ÷ 61? (a) 85 (b) 850 (c) 8500
  19. 19.Best estimate of 2523 ÷ 56? (a) 4200 (b) 42 (c) 420
  20. 20.√67 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.2
  21. 21.Best estimate of 530 ÷ 26? (a) 180 (b) 18 (c) 1800
  22. 22.Best estimate of 494 ÷ 29? (a) 16 (b) 160 (c) 1600
  23. 23.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.7
  24. 24.Best estimate of 1673 ÷ 36? (a) 420 (b) 4200 (c) 42
  25. 25.Best estimate of 8231 ÷ 86? (a) 91 (b) 910 (c) 9100
  26. 26.√92 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.6 (d) 9.5
  27. 27.√30 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.8
  28. 28.√66 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.1 (d) 8.2
  29. 29.Best estimate of 1110 ÷ 62? (a) 1900 (b) 19 (c) 190
  30. 30.Best estimate of 1442 ÷ 68? (a) 2100 (b) 210 (c) 21
  31. 31.Best estimate of 2453 ÷ 26? (a) 820 (b) 8200 (c) 82
  32. 32.√78 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  33. 33.Best estimate of 2105 ÷ 62? (a) 3500 (b) 350 (c) 35
  34. 34.Best estimate of 2841 ÷ 37? (a) 71 (b) 710 (c) 7100
  35. 35.Best estimate of 3282 ÷ 64? (a) 5500 (b) 55 (c) 550
  36. 36.Best estimate of 2007 ÷ 37? (a) 5000 (b) 50 (c) 500
  37. 37.√77 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.8
  38. 38.Best estimate of 705 ÷ 47? (a) 1400 (b) 14 (c) 140
  39. 39.√35 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.9
  40. 40.√85 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.3 (d) 9.1

Answer key

  1. 70
  2. 4.8
  3. 51
  4. 22
  5. 76
  6. 84
  7. 27
  8. 9.8
  9. 91
  10. 69
  11. 43
  12. 7.8
  13. 28
  14. 87
  15. 40
  16. 14
  17. 6.8
  18. 85
  19. 42
  20. 8.2
  21. 18
  22. 16
  23. 7.6
  24. 42
  25. 91
  26. 9.6
  27. 5.5
  28. 8.1
  29. 19
  30. 21
  31. 82
  32. 8.8
  33. 35
  34. 71
  35. 55
  36. 50
  37. 8.8
  38. 14
  39. 5.9
  40. 9.2

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