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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 206 · 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.√28 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.4 (d) 5.2
  2. 2.√70 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.3
  3. 3.Best estimate of 3591 ÷ 53? (a) 72 (b) 7200 (c) 720
  4. 4.√20 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.5
  5. 5.Best estimate of 3480 ÷ 43? (a) 870 (b) 8700 (c) 87
  6. 6.√86 to 1 decimal place? (a) 9.4 (b) 9.1 (c) 9.2 (d) 9.3
  7. 7.Best estimate of 3493 ÷ 41? (a) 8700 (b) 87 (c) 870
  8. 8.Best estimate of 1859 ÷ 22? (a) 9300 (b) 93 (c) 930
  9. 9.√46 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.6 (d) 6.7
  10. 10.Best estimate of 375 ÷ 28? (a) 1300 (b) 13 (c) 130
  11. 11.Best estimate of 2811 ÷ 88? (a) 3100 (b) 310 (c) 31
  12. 12.Best estimate of 4265 ÷ 52? (a) 850 (b) 8500 (c) 85
  13. 13.Best estimate of 3185 ÷ 48? (a) 64 (b) 640 (c) 6400
  14. 14.Best estimate of 1356 ÷ 66? (a) 190 (b) 1900 (c) 19
  15. 15.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2
  16. 16.Best estimate of 5809 ÷ 86? (a) 6500 (b) 650 (c) 65
  17. 17.Best estimate of 7102 ÷ 79? (a) 8900 (b) 89 (c) 890
  18. 18.Best estimate of 3234 ÷ 43? (a) 810 (b) 81 (c) 8100
  19. 19.Best estimate of 2359 ÷ 47? (a) 470 (b) 4700 (c) 47
  20. 20.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.4
  21. 21.√35 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.1 (d) 6.0
  22. 22.Best estimate of 4766 ÷ 66? (a) 68 (b) 680 (c) 6800
  23. 23.√34 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.8
  24. 24.Best estimate of 2545 ÷ 36? (a) 640 (b) 6400 (c) 64
  25. 25.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  26. 26.Best estimate of 529 ÷ 22? (a) 2600 (b) 260 (c) 26
  27. 27.Best estimate of 2100 ÷ 26? (a) 700 (b) 70 (c) 7000
  28. 28.Best estimate of 1213 ÷ 76? (a) 150 (b) 15 (c) 1500
  29. 29.Best estimate of 3963 ÷ 67? (a) 57 (b) 570 (c) 5700
  30. 30.Best estimate of 4761 ÷ 76? (a) 600 (b) 60 (c) 6000
  31. 31.Best estimate of 3363 ÷ 39? (a) 840 (b) 84 (c) 8400
  32. 32.Best estimate of 1819 ÷ 29? (a) 61 (b) 6100 (c) 610
  33. 33.Best estimate of 2142 ÷ 24? (a) 1070 (b) 10700 (c) 107
  34. 34.Best estimate of 2794 ÷ 67? (a) 40 (b) 4000 (c) 400
  35. 35.Best estimate of 2907 ÷ 61? (a) 48 (b) 4800 (c) 480
  36. 36.√40 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.3 (d) 6.5
  37. 37.Best estimate of 1249 ÷ 26? (a) 4200 (b) 420 (c) 42
  38. 38.Best estimate of 6542 ÷ 78? (a) 82 (b) 820 (c) 8200
  39. 39.√41 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.7 (d) 6.6
  40. 40.Best estimate of 6247 ÷ 84? (a) 780 (b) 78 (c) 7800

Answer key

  1. 5.3
  2. 8.4
  3. 72
  4. 4.5
  5. 87
  6. 9.3
  7. 87
  8. 93
  9. 6.8
  10. 13
  11. 31
  12. 85
  13. 64
  14. 19
  15. 6.2
  16. 65
  17. 89
  18. 81
  19. 47
  20. 9.6
  21. 5.9
  22. 68
  23. 5.8
  24. 64
  25. 4.9
  26. 26
  27. 70
  28. 15
  29. 57
  30. 60
  31. 84
  32. 61
  33. 107
  34. 40
  35. 48
  36. 6.3
  37. 42
  38. 82
  39. 6.4
  40. 78

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