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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 582 · 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 2248 ÷ 61? (a) 3700 (b) 370 (c) 37
  2. 2.√70 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.2
  3. 3.√89 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.5 (d) 9.4
  4. 4.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  5. 5.Best estimate of 2780 ÷ 78? (a) 350 (b) 35 (c) 3500
  6. 6.Best estimate of 3130 ÷ 84? (a) 390 (b) 3900 (c) 39
  7. 7.√72 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.2
  8. 8.√58 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.8 (d) 7.7
  9. 9.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.4 (d) 8.2
  10. 10.√82 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  11. 11.√50 to 1 decimal place? (a) 7.0 (b) 7.3 (c) 7.2 (d) 7.1
  12. 12.Best estimate of 1026 ÷ 52? (a) 210 (b) 2100 (c) 21
  13. 13.√75 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.7 (d) 8.9
  14. 14.√76 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.8 (d) 8.9
  15. 15.√22 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.8 (d) 4.5
  16. 16.√92 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  17. 17.Best estimate of 4481 ÷ 54? (a) 9000 (b) 90 (c) 900
  18. 18.Best estimate of 2848 ÷ 36? (a) 7100 (b) 71 (c) 710
  19. 19.Best estimate of 5137 ÷ 56? (a) 8600 (b) 860 (c) 86
  20. 20.Best estimate of 507 ÷ 26? (a) 17 (b) 170 (c) 1700
  21. 21.√42 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.6
  22. 22.Best estimate of 825 ÷ 21? (a) 41 (b) 410 (c) 4100
  23. 23.√78 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.8
  24. 24.√56 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.4 (d) 7.5
  25. 25.Best estimate of 1420 ÷ 44? (a) 36 (b) 3600 (c) 360
  26. 26.√83 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 8.9 (d) 9.1
  27. 27.√21 to 1 decimal place? (a) 4.6 (b) 4.3 (c) 4.5 (d) 4.4
  28. 28.Best estimate of 1665 ÷ 62? (a) 2800 (b) 280 (c) 28
  29. 29.Best estimate of 4657 ÷ 54? (a) 930 (b) 9300 (c) 93
  30. 30.√61 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.8 (d) 7.5
  31. 31.Best estimate of 1901 ÷ 46? (a) 38 (b) 3800 (c) 380
  32. 32.√23 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.7 (d) 4.8
  33. 33.Best estimate of 712 ÷ 47? (a) 14 (b) 1400 (c) 140
  34. 34.√84 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.3 (d) 9.4
  35. 35.Best estimate of 1916 ÷ 22? (a) 960 (b) 96 (c) 9600
  36. 36.Best estimate of 1935 ÷ 31? (a) 650 (b) 65 (c) 6500
  37. 37.Best estimate of 1989 ÷ 21? (a) 99 (b) 9900 (c) 990
  38. 38.√41 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.3 (d) 6.4
  39. 39.Best estimate of 5593 ÷ 62? (a) 93 (b) 9300 (c) 930
  40. 40.Best estimate of 1333 ÷ 31? (a) 4400 (b) 44 (c) 440

Answer key

  1. 37
  2. 8.4
  3. 9.4
  4. 9.7
  5. 35
  6. 39
  7. 8.5
  8. 7.6
  9. 8.3
  10. 9.1
  11. 7.1
  12. 21
  13. 8.7
  14. 8.7
  15. 4.7
  16. 9.6
  17. 90
  18. 71
  19. 86
  20. 17
  21. 6.5
  22. 41
  23. 8.8
  24. 7.5
  25. 36
  26. 9.1
  27. 4.6
  28. 28
  29. 93
  30. 7.8
  31. 38
  32. 4.8
  33. 14
  34. 9.2
  35. 96
  36. 65
  37. 99
  38. 6.4
  39. 93
  40. 44

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