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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 988 · 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 1316 ÷ 32? (a) 440 (b) 44 (c) 4400
  2. 2.√88 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  3. 3.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.1 (d) 9.8
  4. 4.Best estimate of 931 ÷ 31? (a) 310 (b) 3100 (c) 31
  5. 5.√21 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.6 (d) 4.9
  6. 6.√23 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.6 (d) 4.8
  7. 7.Best estimate of 849 ÷ 32? (a) 280 (b) 28 (c) 2800
  8. 8.Best estimate of 2522 ÷ 64? (a) 420 (b) 42 (c) 4200
  9. 9.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  10. 10.√31 to 1 decimal place? (a) 5.4 (b) 5.7 (c) 5.6 (d) 5.5
  11. 11.Best estimate of 4731 ÷ 68? (a) 6800 (b) 68 (c) 680
  12. 12.√30 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.7
  13. 13.Best estimate of 3010 ÷ 53? (a) 6000 (b) 60 (c) 600
  14. 14.Best estimate of 2763 ÷ 32? (a) 920 (b) 92 (c) 9200
  15. 15.√47 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.0 (d) 7.1
  16. 16.√80 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.2 (d) 9.0
  17. 17.Best estimate of 2942 ÷ 86? (a) 330 (b) 3300 (c) 33
  18. 18.Best estimate of 6059 ÷ 86? (a) 670 (b) 67 (c) 6700
  19. 19.Best estimate of 558 ÷ 33? (a) 19 (b) 1900 (c) 190
  20. 20.√89 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.6 (d) 9.4
  21. 21.Best estimate of 2068 ÷ 32? (a) 690 (b) 6900 (c) 69
  22. 22.Best estimate of 3322 ÷ 63? (a) 55 (b) 5500 (c) 550
  23. 23.Best estimate of 2383 ÷ 83? (a) 300 (b) 30 (c) 3000
  24. 24.√94 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  25. 25.Best estimate of 7909 ÷ 88? (a) 8800 (b) 88 (c) 880
  26. 26.Best estimate of 2456 ÷ 36? (a) 61 (b) 6100 (c) 610
  27. 27.Best estimate of 2655 ÷ 38? (a) 66 (b) 6600 (c) 660
  28. 28.Best estimate of 6239 ÷ 77? (a) 780 (b) 78 (c) 7800
  29. 29.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.2
  30. 30.Best estimate of 1611 ÷ 22? (a) 8100 (b) 81 (c) 810
  31. 31.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 6.9 (d) 7.0
  32. 32.Best estimate of 3207 ÷ 56? (a) 530 (b) 5300 (c) 53
  33. 33.Best estimate of 5488 ÷ 68? (a) 780 (b) 7800 (c) 78
  34. 34.Best estimate of 590 ÷ 48? (a) 1200 (b) 120 (c) 12
  35. 35.√76 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.5 (d) 8.6
  36. 36.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.7 (d) 5.8
  37. 37.√69 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.3 (d) 8.2
  38. 38.Best estimate of 1825 ÷ 56? (a) 3000 (b) 30 (c) 300
  39. 39.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  40. 40.√38 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.0

Answer key

  1. 44
  2. 9.4
  3. 9.8
  4. 31
  5. 4.6
  6. 4.8
  7. 28
  8. 42
  9. 7.6
  10. 5.6
  11. 68
  12. 5.5
  13. 60
  14. 92
  15. 6.9
  16. 8.9
  17. 33
  18. 67
  19. 19
  20. 9.4
  21. 69
  22. 55
  23. 30
  24. 9.7
  25. 88
  26. 61
  27. 66
  28. 78
  29. 7.4
  30. 81
  31. 7.1
  32. 53
  33. 78
  34. 12
  35. 8.7
  36. 5.8
  37. 8.3
  38. 30
  39. 6.1
  40. 6.2

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