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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 788 · 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.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  2. 2.Best estimate of 2074 ÷ 28? (a) 690 (b) 6900 (c) 69
  3. 3.√85 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  4. 4.Best estimate of 2051 ÷ 89? (a) 2300 (b) 230 (c) 23
  5. 5.√58 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.8 (d) 7.6
  6. 6.Best estimate of 895 ÷ 66? (a) 130 (b) 1300 (c) 13
  7. 7.√44 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.9 (d) 6.7
  8. 8.√27 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  9. 9.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.5
  10. 10.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 6.2
  11. 11.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  12. 12.Best estimate of 3238 ÷ 59? (a) 540 (b) 5400 (c) 54
  13. 13.Best estimate of 731 ÷ 36? (a) 1800 (b) 18 (c) 180
  14. 14.√74 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.6 (d) 8.5
  15. 15.Best estimate of 2048 ÷ 26? (a) 680 (b) 6800 (c) 68
  16. 16.Best estimate of 2249 ÷ 27? (a) 7500 (b) 75 (c) 750
  17. 17.Best estimate of 4775 ÷ 56? (a) 8000 (b) 800 (c) 80
  18. 18.√76 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  19. 19.Best estimate of 1610 ÷ 33? (a) 54 (b) 5400 (c) 540
  20. 20.Best estimate of 3043 ÷ 56? (a) 510 (b) 51 (c) 5100
  21. 21.Best estimate of 4587 ÷ 52? (a) 9200 (b) 92 (c) 920
  22. 22.Best estimate of 5721 ÷ 67? (a) 820 (b) 8200 (c) 82
  23. 23.√55 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.4 (d) 7.5
  24. 24.Best estimate of 1719 ÷ 86? (a) 1900 (b) 190 (c) 19
  25. 25.Best estimate of 1127 ÷ 26? (a) 380 (b) 3800 (c) 38
  26. 26.Best estimate of 3100 ÷ 33? (a) 10300 (b) 103 (c) 1030
  27. 27.Best estimate of 4015 ÷ 76? (a) 50 (b) 5000 (c) 500
  28. 28.Best estimate of 1225 ÷ 38? (a) 31 (b) 3100 (c) 310
  29. 29.√45 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.8 (d) 6.7
  30. 30.Best estimate of 3606 ÷ 48? (a) 72 (b) 7200 (c) 720
  31. 31.Best estimate of 4994 ÷ 84? (a) 620 (b) 62 (c) 6200
  32. 32.√69 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 8.3
  33. 33.Best estimate of 2545 ÷ 28? (a) 85 (b) 8500 (c) 850
  34. 34.√83 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.0 (d) 9.1
  35. 35.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  36. 36.Best estimate of 1320 ÷ 22? (a) 660 (b) 6600 (c) 66
  37. 37.√24 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.9
  38. 38.Best estimate of 3036 ÷ 36? (a) 760 (b) 76 (c) 7600
  39. 39.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.0
  40. 40.√89 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.6 (d) 9.4

Answer key

  1. 5.8
  2. 69
  3. 9.2
  4. 23
  5. 7.6
  6. 13
  7. 6.6
  8. 5.2
  9. 6.2
  10. 5.9
  11. 9.8
  12. 54
  13. 18
  14. 8.6
  15. 68
  16. 75
  17. 80
  18. 8.7
  19. 54
  20. 51
  21. 92
  22. 82
  23. 7.4
  24. 19
  25. 38
  26. 103
  27. 50
  28. 31
  29. 6.7
  30. 72
  31. 62
  32. 8.3
  33. 85
  34. 9.1
  35. 9.1
  36. 66
  37. 4.9
  38. 76
  39. 6.1
  40. 9.4

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