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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 735 · 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.√90 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6
  2. 2.Best estimate of 2418 ÷ 29? (a) 810 (b) 81 (c) 8100
  3. 3.Best estimate of 1634 ÷ 86? (a) 18 (b) 1800 (c) 180
  4. 4.Best estimate of 2232 ÷ 86? (a) 25 (b) 2500 (c) 250
  5. 5.Best estimate of 1631 ÷ 28? (a) 540 (b) 54 (c) 5400
  6. 6.Best estimate of 1524 ÷ 62? (a) 2500 (b) 25 (c) 250
  7. 7.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 4.9 (d) 5.0
  8. 8.Best estimate of 1658 ÷ 37? (a) 410 (b) 41 (c) 4100
  9. 9.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.4
  10. 10.√44 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.5
  11. 11.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  12. 12.Best estimate of 1685 ÷ 33? (a) 5600 (b) 56 (c) 560
  13. 13.√53 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.5 (d) 7.4
  14. 14.Best estimate of 1095 ÷ 82? (a) 140 (b) 14 (c) 1400
  15. 15.Best estimate of 1508 ÷ 82? (a) 190 (b) 19 (c) 1900
  16. 16.√50 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.1 (d) 7.0
  17. 17.Best estimate of 2073 ÷ 26? (a) 69 (b) 690 (c) 6900
  18. 18.√67 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  19. 19.Best estimate of 1966 ÷ 21? (a) 98 (b) 980 (c) 9800
  20. 20.Best estimate of 1011 ÷ 34? (a) 340 (b) 34 (c) 3400
  21. 21.Best estimate of 6301 ÷ 82? (a) 7900 (b) 790 (c) 79
  22. 22.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.4
  23. 23.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  24. 24.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.1 (d) 6.2
  25. 25.Best estimate of 1625 ÷ 46? (a) 330 (b) 33 (c) 3300
  26. 26.Best estimate of 1457 ÷ 22? (a) 73 (b) 7300 (c) 730
  27. 27.Best estimate of 5540 ÷ 78? (a) 6900 (b) 69 (c) 690
  28. 28.Best estimate of 7257 ÷ 76? (a) 910 (b) 9100 (c) 91
  29. 29.√35 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.9
  30. 30.Best estimate of 5695 ÷ 72? (a) 810 (b) 81 (c) 8100
  31. 31.√76 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.8 (d) 8.9
  32. 32.Best estimate of 5179 ÷ 54? (a) 10400 (b) 104 (c) 1040
  33. 33.Best estimate of 1431 ÷ 43? (a) 3600 (b) 36 (c) 360
  34. 34.Best estimate of 2366 ÷ 36? (a) 59 (b) 590 (c) 5900
  35. 35.√30 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.5
  36. 36.Best estimate of 647 ÷ 23? (a) 320 (b) 3200 (c) 32
  37. 37.Best estimate of 1138 ÷ 81? (a) 14 (b) 1400 (c) 140
  38. 38.√28 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.4 (d) 5.2
  39. 39.Best estimate of 1989 ÷ 36? (a) 500 (b) 50 (c) 5000
  40. 40.Best estimate of 2842 ÷ 32? (a) 9500 (b) 950 (c) 95

Answer key

  1. 9.5
  2. 81
  3. 18
  4. 25
  5. 54
  6. 25
  7. 5.1
  8. 41
  9. 6.1
  10. 6.6
  11. 9.8
  12. 56
  13. 7.3
  14. 14
  15. 19
  16. 7.1
  17. 69
  18. 8.2
  19. 98
  20. 34
  21. 79
  22. 5.6
  23. 9.6
  24. 6.3
  25. 33
  26. 73
  27. 69
  28. 91
  29. 5.9
  30. 81
  31. 8.7
  32. 104
  33. 36
  34. 59
  35. 5.5
  36. 32
  37. 14
  38. 5.3
  39. 50
  40. 95

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