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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 914 · 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.√90 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.4
  2. 2.Best estimate of 5092 ÷ 62? (a) 8500 (b) 850 (c) 85
  3. 3.√28 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.4 (d) 5.6
  4. 4.Best estimate of 1454 ÷ 36? (a) 360 (b) 3600 (c) 36
  5. 5.Best estimate of 2985 ÷ 46? (a) 6000 (b) 60 (c) 600
  6. 6.√88 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.4 (d) 9.5
  7. 7.Best estimate of 2163 ÷ 74? (a) 31 (b) 310 (c) 3100
  8. 8.Best estimate of 674 ÷ 42? (a) 17 (b) 1700 (c) 170
  9. 9.√24 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.7 (d) 4.9
  10. 10.√56 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.4 (d) 7.6
  11. 11.Best estimate of 5436 ÷ 62? (a) 91 (b) 9100 (c) 910
  12. 12.Best estimate of 2900 ÷ 36? (a) 73 (b) 7300 (c) 730
  13. 13.Best estimate of 2787 ÷ 32? (a) 93 (b) 9300 (c) 930
  14. 14.Best estimate of 3844 ÷ 59? (a) 64 (b) 6400 (c) 640
  15. 15.Best estimate of 2542 ÷ 49? (a) 5100 (b) 510 (c) 51
  16. 16.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.3
  17. 17.√45 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.7 (d) 6.5
  18. 18.Best estimate of 2388 ÷ 26? (a) 8000 (b) 800 (c) 80
  19. 19.√74 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.8 (d) 8.6
  20. 20.Best estimate of 763 ÷ 31? (a) 2500 (b) 250 (c) 25
  21. 21.Best estimate of 2625 ÷ 56? (a) 4400 (b) 44 (c) 440
  22. 22.√44 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.6 (d) 6.5
  23. 23.Best estimate of 1767 ÷ 27? (a) 590 (b) 5900 (c) 59
  24. 24.Best estimate of 2855 ÷ 61? (a) 4800 (b) 480 (c) 48
  25. 25.Best estimate of 1299 ÷ 27? (a) 43 (b) 4300 (c) 430
  26. 26.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.3 (d) 6.0
  27. 27.√22 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.8 (d) 4.6
  28. 28.Best estimate of 868 ÷ 36? (a) 22 (b) 220 (c) 2200
  29. 29.Best estimate of 5060 ÷ 62? (a) 8400 (b) 84 (c) 840
  30. 30.Best estimate of 2479 ÷ 79? (a) 310 (b) 31 (c) 3100
  31. 31.Best estimate of 1339 ÷ 61? (a) 220 (b) 2200 (c) 22
  32. 32.√59 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.6 (d) 7.4
  33. 33.Best estimate of 1071 ÷ 43? (a) 27 (b) 2700 (c) 270
  34. 34.Best estimate of 5295 ÷ 67? (a) 7600 (b) 76 (c) 760
  35. 35.Best estimate of 3495 ÷ 42? (a) 870 (b) 87 (c) 8700
  36. 36.Best estimate of 1104 ÷ 64? (a) 1800 (b) 18 (c) 180
  37. 37.Best estimate of 1205 ÷ 82? (a) 150 (b) 15 (c) 1500
  38. 38.√62 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.7 (d) 7.8
  39. 39.√71 to 1 decimal place? (a) 8.6 (b) 8.3 (c) 8.4 (d) 8.5
  40. 40.√78 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.8

Answer key

  1. 9.5
  2. 85
  3. 5.3
  4. 36
  5. 60
  6. 9.4
  7. 31
  8. 17
  9. 4.9
  10. 7.5
  11. 91
  12. 73
  13. 93
  14. 64
  15. 51
  16. 9.6
  17. 6.7
  18. 80
  19. 8.6
  20. 25
  21. 44
  22. 6.6
  23. 59
  24. 48
  25. 43
  26. 6.1
  27. 4.7
  28. 22
  29. 84
  30. 31
  31. 22
  32. 7.7
  33. 27
  34. 76
  35. 87
  36. 18
  37. 15
  38. 7.9
  39. 8.4
  40. 8.8

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