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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 856 · 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.√47 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.9 (d) 6.8
  2. 2.√80 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 9.2
  3. 3.Best estimate of 2418 ÷ 39? (a) 6000 (b) 600 (c) 60
  4. 4.Best estimate of 3168 ÷ 36? (a) 790 (b) 7900 (c) 79
  5. 5.Best estimate of 879 ÷ 38? (a) 22 (b) 220 (c) 2200
  6. 6.√55 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.4 (d) 7.5
  7. 7.√23 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.9 (d) 4.7
  8. 8.Best estimate of 3155 ÷ 52? (a) 63 (b) 630 (c) 6300
  9. 9.Best estimate of 4011 ÷ 46? (a) 80 (b) 8000 (c) 800
  10. 10.√41 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.5 (d) 6.4
  11. 11.Best estimate of 1919 ÷ 26? (a) 6400 (b) 64 (c) 640
  12. 12.Best estimate of 1931 ÷ 77? (a) 24 (b) 2400 (c) 240
  13. 13.Best estimate of 4851 ÷ 51? (a) 9700 (b) 970 (c) 97
  14. 14.√89 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.4 (d) 9.6
  15. 15.Best estimate of 903 ÷ 28? (a) 3000 (b) 30 (c) 300
  16. 16.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.6
  17. 17.Best estimate of 1766 ÷ 26? (a) 590 (b) 59 (c) 5900
  18. 18.Best estimate of 2028 ÷ 27? (a) 6800 (b) 68 (c) 680
  19. 19.Best estimate of 1728 ÷ 72? (a) 250 (b) 2500 (c) 25
  20. 20.Best estimate of 3247 ÷ 63? (a) 54 (b) 5400 (c) 540
  21. 21.Best estimate of 1705 ÷ 27? (a) 570 (b) 5700 (c) 57
  22. 22.Best estimate of 4122 ÷ 86? (a) 46 (b) 460 (c) 4600
  23. 23.Best estimate of 5253 ÷ 62? (a) 8800 (b) 880 (c) 88
  24. 24.Best estimate of 7143 ÷ 81? (a) 8900 (b) 890 (c) 89
  25. 25.Best estimate of 662 ÷ 29? (a) 220 (b) 22 (c) 2200
  26. 26.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.5
  27. 27.Best estimate of 4110 ÷ 63? (a) 69 (b) 6900 (c) 690
  28. 28.Best estimate of 4017 ÷ 48? (a) 800 (b) 80 (c) 8000
  29. 29.Best estimate of 5074 ÷ 66? (a) 7200 (b) 72 (c) 720
  30. 30.√74 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.6
  31. 31.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 6.3
  32. 32.Best estimate of 979 ÷ 66? (a) 140 (b) 1400 (c) 14
  33. 33.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  34. 34.√88 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.7
  35. 35.√35 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.6 (d) 5.7
  36. 36.Best estimate of 4060 ÷ 43? (a) 102 (b) 10200 (c) 1020
  37. 37.√92 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.5
  38. 38.Best estimate of 1529 ÷ 72? (a) 22 (b) 220 (c) 2200
  39. 39.Best estimate of 3982 ÷ 46? (a) 8000 (b) 80 (c) 800
  40. 40.Best estimate of 1834 ÷ 37? (a) 460 (b) 46 (c) 4600

Answer key

  1. 6.9
  2. 8.9
  3. 60
  4. 79
  5. 22
  6. 7.4
  7. 4.8
  8. 63
  9. 80
  10. 6.4
  11. 64
  12. 24
  13. 97
  14. 9.4
  15. 30
  16. 6.3
  17. 59
  18. 68
  19. 25
  20. 54
  21. 57
  22. 46
  23. 88
  24. 89
  25. 22
  26. 7.6
  27. 69
  28. 80
  29. 72
  30. 8.6
  31. 6.1
  32. 14
  33. 9.7
  34. 9.4
  35. 5.9
  36. 102
  37. 9.6
  38. 22
  39. 80
  40. 46

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