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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 661 · 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.√40 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.1 (d) 6.3
  2. 2.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.9
  3. 3.Best estimate of 5634 ÷ 82? (a) 70 (b) 7000 (c) 700
  4. 4.√45 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.9 (d) 6.7
  5. 5.Best estimate of 305 ÷ 23? (a) 15 (b) 150 (c) 1500
  6. 6.√69 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.3 (d) 8.5
  7. 7.Best estimate of 2844 ÷ 43? (a) 71 (b) 7100 (c) 710
  8. 8.Best estimate of 3147 ÷ 33? (a) 1050 (b) 10500 (c) 105
  9. 9.Best estimate of 621 ÷ 24? (a) 310 (b) 31 (c) 3100
  10. 10.√82 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 9.3
  11. 11.Best estimate of 8147 ÷ 89? (a) 910 (b) 9100 (c) 91
  12. 12.Best estimate of 2266 ÷ 89? (a) 2500 (b) 250 (c) 25
  13. 13.Best estimate of 1745 ÷ 89? (a) 190 (b) 1900 (c) 19
  14. 14.Best estimate of 3122 ÷ 36? (a) 7800 (b) 78 (c) 780
  15. 15.Best estimate of 652 ÷ 49? (a) 130 (b) 1300 (c) 13
  16. 16.Best estimate of 3608 ÷ 62? (a) 600 (b) 6000 (c) 60
  17. 17.Best estimate of 2931 ÷ 89? (a) 330 (b) 3300 (c) 33
  18. 18.Best estimate of 3244 ÷ 53? (a) 650 (b) 65 (c) 6500
  19. 19.√48 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 6.7
  20. 20.Best estimate of 864 ÷ 36? (a) 2200 (b) 22 (c) 220
  21. 21.√71 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.7 (d) 8.6
  22. 22.√37 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 6.3
  23. 23.Best estimate of 1843 ÷ 27? (a) 6100 (b) 61 (c) 610
  24. 24.Best estimate of 635 ÷ 24? (a) 320 (b) 32 (c) 3200
  25. 25.Best estimate of 3220 ÷ 72? (a) 460 (b) 46 (c) 4600
  26. 26.√58 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.5 (d) 7.4
  27. 27.Best estimate of 511 ÷ 37? (a) 130 (b) 1300 (c) 13
  28. 28.Best estimate of 963 ÷ 72? (a) 140 (b) 1400 (c) 14
  29. 29.√92 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.7
  30. 30.√88 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.6 (d) 9.5
  31. 31.√24 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 4.9 (d) 5.0
  32. 32.√78 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.8 (d) 8.9
  33. 33.Best estimate of 2337 ÷ 88? (a) 2600 (b) 26 (c) 260
  34. 34.Best estimate of 942 ÷ 49? (a) 19 (b) 1900 (c) 190
  35. 35.√50 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.4 (d) 7.2
  36. 36.Best estimate of 2866 ÷ 46? (a) 5700 (b) 57 (c) 570
  37. 37.√61 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.7 (d) 7.9
  38. 38.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  39. 39.√43 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.5 (d) 6.6
  40. 40.Best estimate of 2342 ÷ 29? (a) 780 (b) 78 (c) 7800

Answer key

  1. 6.3
  2. 9.7
  3. 70
  4. 6.7
  5. 15
  6. 8.3
  7. 71
  8. 105
  9. 31
  10. 9.1
  11. 91
  12. 25
  13. 19
  14. 78
  15. 13
  16. 60
  17. 33
  18. 65
  19. 6.9
  20. 22
  21. 8.4
  22. 6.1
  23. 61
  24. 32
  25. 46
  26. 7.6
  27. 13
  28. 14
  29. 9.6
  30. 9.4
  31. 4.9
  32. 8.8
  33. 26
  34. 19
  35. 7.1
  36. 57
  37. 7.8
  38. 8.6
  39. 6.6
  40. 78

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