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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 715 · 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 2034 ÷ 34? (a) 68 (b) 680 (c) 6800
  2. 2.√98 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.2 (d) 10.1
  3. 3.√44 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.4
  4. 4.Best estimate of 1032 ÷ 29? (a) 340 (b) 34 (c) 3400
  5. 5.Best estimate of 5530 ÷ 86? (a) 6100 (b) 61 (c) 610
  6. 6.√74 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.4
  7. 7.Best estimate of 830 ÷ 22? (a) 420 (b) 4200 (c) 42
  8. 8.Best estimate of 2845 ÷ 81? (a) 3600 (b) 36 (c) 360
  9. 9.Best estimate of 5287 ÷ 72? (a) 76 (b) 7600 (c) 760
  10. 10.Best estimate of 2816 ÷ 84? (a) 35 (b) 3500 (c) 350
  11. 11.√76 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  12. 12.Best estimate of 4719 ÷ 57? (a) 79 (b) 790 (c) 7900
  13. 13.Best estimate of 1660 ÷ 24? (a) 830 (b) 83 (c) 8300
  14. 14.√62 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.2 (d) 8.1
  15. 15.√69 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 8.3
  16. 16.Best estimate of 942 ÷ 22? (a) 4700 (b) 470 (c) 47
  17. 17.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.4
  18. 18.√59 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.8
  19. 19.Best estimate of 1623 ÷ 24? (a) 8100 (b) 810 (c) 81
  20. 20.Best estimate of 2208 ÷ 54? (a) 44 (b) 4400 (c) 440
  21. 21.Best estimate of 3374 ÷ 42? (a) 840 (b) 84 (c) 8400
  22. 22.Best estimate of 2146 ÷ 32? (a) 7200 (b) 720 (c) 72
  23. 23.Best estimate of 2352 ÷ 88? (a) 2600 (b) 26 (c) 260
  24. 24.√47 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 6.8 (d) 7.0
  25. 25.Best estimate of 1153 ÷ 62? (a) 19 (b) 190 (c) 1900
  26. 26.Best estimate of 2796 ÷ 57? (a) 470 (b) 4700 (c) 47
  27. 27.Best estimate of 4011 ÷ 64? (a) 67 (b) 670 (c) 6700
  28. 28.Best estimate of 1550 ÷ 28? (a) 5200 (b) 520 (c) 52
  29. 29.Best estimate of 6063 ÷ 82? (a) 760 (b) 7600 (c) 76
  30. 30.√45 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 6.6
  31. 31.Best estimate of 3245 ÷ 52? (a) 650 (b) 6500 (c) 65
  32. 32.√86 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 9.3
  33. 33.Best estimate of 785 ÷ 41? (a) 2000 (b) 200 (c) 20
  34. 34.Best estimate of 3979 ÷ 56? (a) 660 (b) 66 (c) 6600
  35. 35.Best estimate of 1491 ÷ 61? (a) 250 (b) 2500 (c) 25
  36. 36.Best estimate of 3608 ÷ 89? (a) 4000 (b) 40 (c) 400
  37. 37.√22 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.6 (d) 4.9
  38. 38.Best estimate of 5100 ÷ 56? (a) 85 (b) 850 (c) 8500
  39. 39.Best estimate of 3061 ÷ 83? (a) 380 (b) 38 (c) 3800
  40. 40.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7

Answer key

  1. 68
  2. 9.9
  3. 6.6
  4. 34
  5. 61
  6. 8.6
  7. 42
  8. 36
  9. 76
  10. 35
  11. 8.7
  12. 79
  13. 83
  14. 7.9
  15. 8.3
  16. 47
  17. 7.1
  18. 7.7
  19. 81
  20. 44
  21. 84
  22. 72
  23. 26
  24. 6.9
  25. 19
  26. 47
  27. 67
  28. 52
  29. 76
  30. 6.7
  31. 65
  32. 9.3
  33. 20
  34. 66
  35. 25
  36. 40
  37. 4.7
  38. 85
  39. 38
  40. 9.8

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