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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 168 · 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.√92 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.7 (d) 9.6
  2. 2.Best estimate of 2736 ÷ 29? (a) 910 (b) 9100 (c) 91
  3. 3.√74 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.9
  4. 4.Best estimate of 1427 ÷ 36? (a) 360 (b) 3600 (c) 36
  5. 5.Best estimate of 6352 ÷ 89? (a) 7100 (b) 71 (c) 710
  6. 6.Best estimate of 2628 ÷ 49? (a) 53 (b) 530 (c) 5300
  7. 7.Best estimate of 1786 ÷ 42? (a) 45 (b) 4500 (c) 450
  8. 8.√21 to 1 decimal place? (a) 4.4 (b) 4.5 (c) 4.6 (d) 4.3
  9. 9.√98 to 1 decimal place? (a) 10.2 (b) 10.0 (c) 10.1 (d) 9.9
  10. 10.Best estimate of 2805 ÷ 63? (a) 470 (b) 47 (c) 4700
  11. 11.Best estimate of 2101 ÷ 81? (a) 260 (b) 2600 (c) 26
  12. 12.Best estimate of 4793 ÷ 52? (a) 9600 (b) 96 (c) 960
  13. 13.Best estimate of 2636 ÷ 62? (a) 44 (b) 440 (c) 4400
  14. 14.Best estimate of 1543 ÷ 32? (a) 5100 (b) 510 (c) 51
  15. 15.√44 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.7 (d) 6.5
  16. 16.Best estimate of 7229 ÷ 88? (a) 80 (b) 800 (c) 8000
  17. 17.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  18. 18.√96 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.9 (d) 10.1
  19. 19.Best estimate of 1770 ÷ 27? (a) 590 (b) 59 (c) 5900
  20. 20.Best estimate of 1887 ÷ 56? (a) 310 (b) 3100 (c) 31
  21. 21.√51 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  22. 22.√26 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.0
  23. 23.Best estimate of 6468 ÷ 69? (a) 92 (b) 9200 (c) 920
  24. 24.Best estimate of 2353 ÷ 49? (a) 47 (b) 470 (c) 4700
  25. 25.√89 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  26. 26.√48 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.9
  27. 27.√72 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.7
  28. 28.Best estimate of 3198 ÷ 34? (a) 10700 (b) 1070 (c) 107
  29. 29.Best estimate of 2965 ÷ 51? (a) 5900 (b) 590 (c) 59
  30. 30.√27 to 1 decimal place? (a) 5.2 (b) 5.5 (c) 5.3 (d) 5.4
  31. 31.Best estimate of 863 ÷ 32? (a) 2900 (b) 290 (c) 29
  32. 32.Best estimate of 1627 ÷ 82? (a) 2000 (b) 20 (c) 200
  33. 33.Best estimate of 491 ÷ 32? (a) 16 (b) 1600 (c) 160
  34. 34.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.0 (d) 5.1
  35. 35.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.8
  36. 36.√62 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.0 (d) 8.1
  37. 37.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.6
  38. 38.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.2 (d) 6.4
  39. 39.√61 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.7 (d) 7.6
  40. 40.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.6 (d) 4.7

Answer key

  1. 9.6
  2. 91
  3. 8.6
  4. 36
  5. 71
  6. 53
  7. 45
  8. 4.6
  9. 9.9
  10. 47
  11. 26
  12. 96
  13. 44
  14. 51
  15. 6.6
  16. 80
  17. 8.4
  18. 9.8
  19. 59
  20. 31
  21. 7.1
  22. 5.1
  23. 92
  24. 47
  25. 9.4
  26. 6.9
  27. 8.5
  28. 107
  29. 59
  30. 5.2
  31. 29
  32. 20
  33. 16
  34. 5.3
  35. 7.6
  36. 7.9
  37. 7.3
  38. 6.3
  39. 7.8
  40. 4.8

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