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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 455 · 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.√86 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.2 (d) 9.4
  2. 2.√52 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.0
  3. 3.Best estimate of 1880 ÷ 21? (a) 940 (b) 9400 (c) 94
  4. 4.√40 to 1 decimal place? (a) 6.1 (b) 6.4 (c) 6.2 (d) 6.3
  5. 5.√59 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.9 (d) 7.7
  6. 6.Best estimate of 1313 ÷ 22? (a) 660 (b) 6600 (c) 66
  7. 7.Best estimate of 6771 ÷ 73? (a) 9700 (b) 970 (c) 97
  8. 8.√87 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.3
  9. 9.Best estimate of 1522 ÷ 52? (a) 300 (b) 30 (c) 3000
  10. 10.Best estimate of 534 ÷ 37? (a) 13 (b) 1300 (c) 130
  11. 11.√62 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 8.2
  12. 12.Best estimate of 979 ÷ 41? (a) 240 (b) 2400 (c) 24
  13. 13.√26 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 5.1 (d) 5.2
  14. 14.Best estimate of 5343 ÷ 82? (a) 670 (b) 67 (c) 6700
  15. 15.√50 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.4
  16. 16.Best estimate of 976 ÷ 27? (a) 3300 (b) 330 (c) 33
  17. 17.Best estimate of 2163 ÷ 23? (a) 108 (b) 10800 (c) 1080
  18. 18.Best estimate of 4219 ÷ 74? (a) 60 (b) 6000 (c) 600
  19. 19.Best estimate of 1769 ÷ 21? (a) 8800 (b) 880 (c) 88
  20. 20.√24 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.9 (d) 5.0
  21. 21.Best estimate of 1466 ÷ 26? (a) 490 (b) 49 (c) 4900
  22. 22.Best estimate of 4077 ÷ 67? (a) 580 (b) 5800 (c) 58
  23. 23.Best estimate of 1831 ÷ 46? (a) 370 (b) 37 (c) 3700
  24. 24.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.9
  25. 25.√82 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.8 (d) 8.9
  26. 26.√21 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.5 (d) 4.7
  27. 27.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  28. 28.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  29. 29.Best estimate of 1064 ÷ 72? (a) 1500 (b) 15 (c) 150
  30. 30.√74 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.3
  31. 31.Best estimate of 1390 ÷ 31? (a) 4600 (b) 460 (c) 46
  32. 32.Best estimate of 7067 ÷ 89? (a) 79 (b) 790 (c) 7900
  33. 33.Best estimate of 4795 ÷ 79? (a) 6000 (b) 600 (c) 60
  34. 34.Best estimate of 3323 ÷ 82? (a) 420 (b) 4200 (c) 42
  35. 35.Best estimate of 2924 ÷ 36? (a) 7300 (b) 73 (c) 730
  36. 36.Best estimate of 6276 ÷ 83? (a) 7800 (b) 78 (c) 780
  37. 37.Best estimate of 607 ÷ 36? (a) 150 (b) 1500 (c) 15
  38. 38.Best estimate of 2193 ÷ 31? (a) 7300 (b) 730 (c) 73
  39. 39.√76 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.8
  40. 40.Best estimate of 1620 ÷ 24? (a) 81 (b) 810 (c) 8100

Answer key

  1. 9.3
  2. 7.2
  3. 94
  4. 6.3
  5. 7.7
  6. 66
  7. 97
  8. 9.3
  9. 30
  10. 13
  11. 7.9
  12. 24
  13. 5.1
  14. 67
  15. 7.1
  16. 33
  17. 108
  18. 60
  19. 88
  20. 4.9
  21. 49
  22. 58
  23. 37
  24. 9.8
  25. 9.1
  26. 4.6
  27. 8.3
  28. 5.8
  29. 15
  30. 8.6
  31. 46
  32. 79
  33. 60
  34. 42
  35. 73
  36. 78
  37. 15
  38. 73
  39. 8.7
  40. 81

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