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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 510 · 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 2575 ÷ 27? (a) 8600 (b) 860 (c) 86
  2. 2.Best estimate of 5930 ÷ 86? (a) 660 (b) 6600 (c) 66
  3. 3.Best estimate of 4845 ÷ 66? (a) 6900 (b) 69 (c) 690
  4. 4.Best estimate of 3570 ÷ 72? (a) 510 (b) 5100 (c) 51
  5. 5.√29 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.4 (d) 5.2
  6. 6.Best estimate of 3674 ÷ 51? (a) 730 (b) 73 (c) 7300
  7. 7.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  8. 8.√58 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.7 (d) 7.8
  9. 9.Best estimate of 6661 ÷ 86? (a) 7400 (b) 74 (c) 740
  10. 10.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  11. 11.√48 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.9
  12. 12.√88 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.7
  13. 13.Best estimate of 1536 ÷ 38? (a) 3800 (b) 38 (c) 380
  14. 14.Best estimate of 2356 ÷ 34? (a) 7900 (b) 790 (c) 79
  15. 15.Best estimate of 4195 ÷ 71? (a) 6000 (b) 600 (c) 60
  16. 16.Best estimate of 1885 ÷ 61? (a) 310 (b) 31 (c) 3100
  17. 17.√50 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 7.1 (d) 6.9
  18. 18.Best estimate of 3911 ÷ 42? (a) 980 (b) 98 (c) 9800
  19. 19.Best estimate of 6293 ÷ 77? (a) 79 (b) 7900 (c) 790
  20. 20.√71 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.3
  21. 21.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.4
  22. 22.Best estimate of 1703 ÷ 49? (a) 340 (b) 3400 (c) 34
  23. 23.√51 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 6.8 (d) 7.0
  24. 24.Best estimate of 2537 ÷ 34? (a) 8500 (b) 85 (c) 850
  25. 25.Best estimate of 5530 ÷ 83? (a) 6900 (b) 690 (c) 69
  26. 26.√59 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.6 (d) 7.5
  27. 27.Best estimate of 2169 ÷ 23? (a) 108 (b) 1080 (c) 10800
  28. 28.Best estimate of 869 ÷ 52? (a) 1700 (b) 17 (c) 170
  29. 29.Best estimate of 2037 ÷ 23? (a) 102 (b) 10200 (c) 1020
  30. 30.Best estimate of 2692 ÷ 33? (a) 900 (b) 90 (c) 9000
  31. 31.Best estimate of 1793 ÷ 46? (a) 360 (b) 3600 (c) 36
  32. 32.Best estimate of 498 ÷ 24? (a) 250 (b) 2500 (c) 25
  33. 33.Best estimate of 3110 ÷ 34? (a) 1040 (b) 104 (c) 10400
  34. 34.Best estimate of 6024 ÷ 84? (a) 750 (b) 7500 (c) 75
  35. 35.Best estimate of 1551 ÷ 43? (a) 3900 (b) 390 (c) 39
  36. 36.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 4.8
  37. 37.Best estimate of 2719 ÷ 52? (a) 5400 (b) 54 (c) 540
  38. 38.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 8.9
  39. 39.√30 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.5
  40. 40.Best estimate of 523 ÷ 41? (a) 130 (b) 1300 (c) 13

Answer key

  1. 86
  2. 66
  3. 69
  4. 51
  5. 5.4
  6. 73
  7. 6.1
  8. 7.6
  9. 74
  10. 9.9
  11. 6.9
  12. 9.4
  13. 38
  14. 79
  15. 60
  16. 31
  17. 7.1
  18. 98
  19. 79
  20. 8.4
  21. 6.6
  22. 34
  23. 7.1
  24. 85
  25. 69
  26. 7.7
  27. 108
  28. 17
  29. 102
  30. 90
  31. 36
  32. 25
  33. 104
  34. 75
  35. 39
  36. 5.1
  37. 54
  38. 9.1
  39. 5.5
  40. 13

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