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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 874 · 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.√89 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.7 (d) 9.5
  2. 2.√67 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.1 (d) 8.0
  3. 3.Best estimate of 2305 ÷ 56? (a) 38 (b) 3800 (c) 380
  4. 4.Best estimate of 2661 ÷ 66? (a) 3800 (b) 380 (c) 38
  5. 5.Best estimate of 2799 ÷ 59? (a) 470 (b) 4700 (c) 47
  6. 6.√32 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.9 (d) 5.7
  7. 7.Best estimate of 4132 ÷ 68? (a) 590 (b) 5900 (c) 59
  8. 8.Best estimate of 807 ÷ 23? (a) 40 (b) 400 (c) 4000
  9. 9.Best estimate of 2475 ÷ 46? (a) 50 (b) 500 (c) 5000
  10. 10.√30 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.5 (d) 5.2
  11. 11.√66 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  12. 12.√52 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.4
  13. 13.Best estimate of 896 ÷ 36? (a) 22 (b) 220 (c) 2200
  14. 14.√76 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.7 (d) 8.6
  15. 15.Best estimate of 1962 ÷ 36? (a) 49 (b) 490 (c) 4900
  16. 16.Best estimate of 3655 ÷ 48? (a) 730 (b) 73 (c) 7300
  17. 17.Best estimate of 3558 ÷ 53? (a) 710 (b) 71 (c) 7100
  18. 18.√98 to 1 decimal place? (a) 10.1 (b) 10.2 (c) 10.0 (d) 9.9
  19. 19.Best estimate of 1101 ÷ 39? (a) 28 (b) 280 (c) 2800
  20. 20.√31 to 1 decimal place? (a) 5.6 (b) 5.3 (c) 5.5 (d) 5.4
  21. 21.√79 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.7 (d) 8.8
  22. 22.√53 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.1 (d) 7.3
  23. 23.Best estimate of 3180 ÷ 43? (a) 8000 (b) 80 (c) 800
  24. 24.Best estimate of 1001 ÷ 32? (a) 33 (b) 330 (c) 3300
  25. 25.Best estimate of 2130 ÷ 76? (a) 270 (b) 2700 (c) 27
  26. 26.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 5.2
  27. 27.√61 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.5 (d) 7.7
  28. 28.√87 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  29. 29.Best estimate of 4626 ÷ 82? (a) 580 (b) 5800 (c) 58
  30. 30.√77 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 8.8
  31. 31.√20 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.4 (d) 4.6
  32. 32.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 6.9
  33. 33.√83 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 8.9 (d) 9.0
  34. 34.Best estimate of 2683 ÷ 58? (a) 4500 (b) 450 (c) 45
  35. 35.√69 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.5 (d) 8.3
  36. 36.√37 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 5.8 (d) 6.0
  37. 37.Best estimate of 1939 ÷ 73? (a) 280 (b) 2800 (c) 28
  38. 38.√65 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.1
  39. 39.√96 to 1 decimal place? (a) 10.0 (b) 10.1 (c) 9.8 (d) 9.9
  40. 40.Best estimate of 3379 ÷ 58? (a) 56 (b) 560 (c) 5600

Answer key

  1. 9.4
  2. 8.2
  3. 38
  4. 38
  5. 47
  6. 5.7
  7. 59
  8. 40
  9. 50
  10. 5.5
  11. 8.1
  12. 7.2
  13. 22
  14. 8.7
  15. 49
  16. 73
  17. 71
  18. 9.9
  19. 28
  20. 5.6
  21. 8.9
  22. 7.3
  23. 80
  24. 33
  25. 27
  26. 5.1
  27. 7.8
  28. 9.3
  29. 58
  30. 8.8
  31. 4.5
  32. 7.1
  33. 9.1
  34. 45
  35. 8.3
  36. 6.1
  37. 28
  38. 8.1
  39. 9.8
  40. 56

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