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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 212 · 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 4266 ÷ 66? (a) 61 (b) 6100 (c) 610
  2. 2.√41 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.4 (d) 6.2
  3. 3.√23 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.6 (d) 4.9
  4. 4.Best estimate of 7412 ÷ 88? (a) 820 (b) 8200 (c) 82
  5. 5.Best estimate of 4565 ÷ 48? (a) 910 (b) 91 (c) 9100
  6. 6.Best estimate of 494 ÷ 32? (a) 160 (b) 1600 (c) 16
  7. 7.Best estimate of 5249 ÷ 56? (a) 870 (b) 87 (c) 8700
  8. 8.√62 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  9. 9.√26 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.1 (d) 5.0
  10. 10.Best estimate of 4032 ÷ 64? (a) 6700 (b) 670 (c) 67
  11. 11.Best estimate of 1287 ÷ 42? (a) 320 (b) 3200 (c) 32
  12. 12.√76 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.8 (d) 8.7
  13. 13.Best estimate of 2011 ÷ 42? (a) 50 (b) 500 (c) 5000
  14. 14.Best estimate of 713 ÷ 37? (a) 18 (b) 180 (c) 1800
  15. 15.Best estimate of 1160 ÷ 42? (a) 290 (b) 2900 (c) 29
  16. 16.√65 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 8.3
  17. 17.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  18. 18.Best estimate of 3405 ÷ 68? (a) 4900 (b) 49 (c) 490
  19. 19.Best estimate of 1583 ÷ 36? (a) 400 (b) 40 (c) 4000
  20. 20.Best estimate of 3256 ÷ 36? (a) 810 (b) 81 (c) 8100
  21. 21.Best estimate of 961 ÷ 61? (a) 1600 (b) 160 (c) 16
  22. 22.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  23. 23.Best estimate of 1229 ÷ 72? (a) 18 (b) 1800 (c) 180
  24. 24.Best estimate of 1641 ÷ 87? (a) 180 (b) 1800 (c) 18
  25. 25.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.9 (d) 9.8
  26. 26.√35 to 1 decimal place? (a) 5.9 (b) 6.2 (c) 6.1 (d) 6.0
  27. 27.Best estimate of 3851 ÷ 86? (a) 4300 (b) 430 (c) 43
  28. 28.√75 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  29. 29.√59 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.6 (d) 7.7
  30. 30.Best estimate of 3815 ÷ 48? (a) 7600 (b) 76 (c) 760
  31. 31.Best estimate of 3055 ÷ 53? (a) 610 (b) 61 (c) 6100
  32. 32.√45 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.8
  33. 33.Best estimate of 1811 ÷ 39? (a) 450 (b) 4500 (c) 45
  34. 34.Best estimate of 794 ÷ 37? (a) 2000 (b) 20 (c) 200
  35. 35.Best estimate of 1661 ÷ 33? (a) 550 (b) 55 (c) 5500
  36. 36.Best estimate of 4166 ÷ 68? (a) 6000 (b) 600 (c) 60
  37. 37.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  38. 38.Best estimate of 1348 ÷ 27? (a) 45 (b) 4500 (c) 450
  39. 39.Best estimate of 6307 ÷ 84? (a) 790 (b) 79 (c) 7900
  40. 40.√43 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.3

Answer key

  1. 61
  2. 6.4
  3. 4.8
  4. 82
  5. 91
  6. 16
  7. 87
  8. 7.9
  9. 5.1
  10. 67
  11. 32
  12. 8.7
  13. 50
  14. 18
  15. 29
  16. 8.1
  17. 5.8
  18. 49
  19. 40
  20. 81
  21. 16
  22. 8.6
  23. 18
  24. 18
  25. 9.7
  26. 5.9
  27. 43
  28. 8.7
  29. 7.7
  30. 76
  31. 61
  32. 6.7
  33. 45
  34. 20
  35. 55
  36. 60
  37. 8.9
  38. 45
  39. 79
  40. 6.6

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