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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 595 · 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 742 ÷ 36? (a) 1900 (b) 19 (c) 190
  2. 2.Best estimate of 2782 ÷ 56? (a) 4600 (b) 46 (c) 460
  3. 3.Best estimate of 960 ÷ 62? (a) 160 (b) 16 (c) 1600
  4. 4.√90 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  5. 5.√48 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.1 (d) 7.0
  6. 6.Best estimate of 1219 ÷ 32? (a) 41 (b) 4100 (c) 410
  7. 7.√50 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 7.1 (d) 6.9
  8. 8.Best estimate of 2271 ÷ 73? (a) 320 (b) 3200 (c) 32
  9. 9.√94 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 10.0 (d) 9.8
  10. 10.Best estimate of 2006 ÷ 54? (a) 4000 (b) 400 (c) 40
  11. 11.Best estimate of 2211 ÷ 26? (a) 740 (b) 7400 (c) 74
  12. 12.√89 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.6
  13. 13.√86 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.3
  14. 14.√37 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 6.1 (d) 5.9
  15. 15.Best estimate of 1782 ÷ 38? (a) 45 (b) 450 (c) 4500
  16. 16.√35 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.9
  17. 17.√31 to 1 decimal place? (a) 5.9 (b) 5.6 (c) 5.8 (d) 5.7
  18. 18.Best estimate of 1339 ÷ 36? (a) 33 (b) 330 (c) 3300
  19. 19.√70 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.4
  20. 20.Best estimate of 2298 ÷ 36? (a) 570 (b) 5700 (c) 57
  21. 21.√22 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.4
  22. 22.Best estimate of 809 ÷ 21? (a) 4000 (b) 400 (c) 40
  23. 23.Best estimate of 6423 ÷ 81? (a) 800 (b) 8000 (c) 80
  24. 24.Best estimate of 2794 ÷ 36? (a) 700 (b) 7000 (c) 70
  25. 25.√69 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5
  26. 26.Best estimate of 814 ÷ 36? (a) 200 (b) 20 (c) 2000
  27. 27.√30 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.6 (d) 5.8
  28. 28.Best estimate of 2788 ÷ 76? (a) 35 (b) 350 (c) 3500
  29. 29.√28 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.3 (d) 5.4
  30. 30.√24 to 1 decimal place? (a) 5.2 (b) 4.9 (c) 5.1 (d) 5.0
  31. 31.Best estimate of 3941 ÷ 46? (a) 790 (b) 79 (c) 7900
  32. 32.√78 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  33. 33.Best estimate of 1302 ÷ 47? (a) 260 (b) 26 (c) 2600
  34. 34.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.4
  35. 35.Best estimate of 4285 ÷ 83? (a) 5400 (b) 54 (c) 540
  36. 36.Best estimate of 5536 ÷ 79? (a) 6900 (b) 690 (c) 69
  37. 37.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 9.2
  38. 38.Best estimate of 2345 ÷ 33? (a) 78 (b) 780 (c) 7800
  39. 39.Best estimate of 3669 ÷ 54? (a) 730 (b) 7300 (c) 73
  40. 40.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.2 (d) 8.1

Answer key

  1. 19
  2. 46
  3. 16
  4. 9.5
  5. 6.9
  6. 41
  7. 7.1
  8. 32
  9. 9.7
  10. 40
  11. 74
  12. 9.4
  13. 9.3
  14. 6.1
  15. 45
  16. 5.9
  17. 5.6
  18. 33
  19. 8.4
  20. 57
  21. 4.7
  22. 40
  23. 80
  24. 70
  25. 8.3
  26. 20
  27. 5.5
  28. 35
  29. 5.3
  30. 4.9
  31. 79
  32. 8.8
  33. 26
  34. 8.6
  35. 54
  36. 69
  37. 9.1
  38. 78
  39. 73
  40. 8.1

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