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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 726 · 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.√75 to 1 decimal place? (a) 8.4 (b) 8.7 (c) 8.5 (d) 8.6
  2. 2.Best estimate of 1864 ÷ 81? (a) 230 (b) 23 (c) 2300
  3. 3.Best estimate of 914 ÷ 29? (a) 300 (b) 30 (c) 3000
  4. 4.√92 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  5. 5.√35 to 1 decimal place? (a) 5.6 (b) 5.9 (c) 5.7 (d) 5.8
  6. 6.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 6.1 (d) 5.9
  7. 7.Best estimate of 904 ÷ 36? (a) 230 (b) 23 (c) 2300
  8. 8.Best estimate of 3898 ÷ 51? (a) 780 (b) 7800 (c) 78
  9. 9.Best estimate of 2966 ÷ 63? (a) 490 (b) 4900 (c) 49
  10. 10.Best estimate of 1421 ÷ 49? (a) 28 (b) 280 (c) 2800
  11. 11.√72 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.5 (d) 8.8
  12. 12.Best estimate of 1182 ÷ 26? (a) 39 (b) 3900 (c) 390
  13. 13.Best estimate of 7775 ÷ 87? (a) 86 (b) 860 (c) 8600
  14. 14.√32 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.5 (d) 5.7
  15. 15.√40 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 6.3
  16. 16.Best estimate of 680 ÷ 42? (a) 170 (b) 1700 (c) 17
  17. 17.Best estimate of 3244 ÷ 82? (a) 410 (b) 41 (c) 4100
  18. 18.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 7.7
  19. 19.Best estimate of 5090 ÷ 62? (a) 850 (b) 8500 (c) 85
  20. 20.Best estimate of 555 ÷ 26? (a) 190 (b) 19 (c) 1900
  21. 21.Best estimate of 2523 ÷ 88? (a) 28 (b) 280 (c) 2800
  22. 22.√56 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.6 (d) 7.4
  23. 23.Best estimate of 755 ÷ 52? (a) 1500 (b) 15 (c) 150
  24. 24.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 10.1
  25. 25.Best estimate of 5940 ÷ 86? (a) 660 (b) 6600 (c) 66
  26. 26.√79 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0
  27. 27.Best estimate of 3301 ÷ 42? (a) 83 (b) 830 (c) 8300
  28. 28.Best estimate of 4312 ÷ 62? (a) 720 (b) 7200 (c) 72
  29. 29.√90 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.8
  30. 30.√38 to 1 decimal place? (a) 6.2 (b) 5.9 (c) 6.0 (d) 6.1
  31. 31.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.7
  32. 32.Best estimate of 1854 ÷ 41? (a) 46 (b) 4600 (c) 460
  33. 33.Best estimate of 3385 ÷ 84? (a) 4200 (b) 420 (c) 42
  34. 34.√77 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.8 (d) 8.7
  35. 35.Best estimate of 788 ÷ 26? (a) 26 (b) 260 (c) 2600
  36. 36.Best estimate of 2776 ÷ 42? (a) 69 (b) 690 (c) 6900
  37. 37.Best estimate of 1866 ÷ 21? (a) 930 (b) 9300 (c) 93
  38. 38.Best estimate of 1066 ÷ 43? (a) 270 (b) 27 (c) 2700
  39. 39.Best estimate of 6847 ÷ 82? (a) 860 (b) 86 (c) 8600
  40. 40.Best estimate of 2745 ÷ 56? (a) 460 (b) 46 (c) 4600

Answer key

  1. 8.7
  2. 23
  3. 30
  4. 9.6
  5. 5.9
  6. 5.8
  7. 23
  8. 78
  9. 49
  10. 28
  11. 8.5
  12. 39
  13. 86
  14. 5.7
  15. 6.3
  16. 17
  17. 41
  18. 7.8
  19. 85
  20. 19
  21. 28
  22. 7.5
  23. 15
  24. 9.8
  25. 66
  26. 8.9
  27. 83
  28. 72
  29. 9.5
  30. 6.2
  31. 7.6
  32. 46
  33. 42
  34. 8.8
  35. 26
  36. 69
  37. 93
  38. 27
  39. 86
  40. 46

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