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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 689 · 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.√82 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 9.1
  2. 2.√74 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.8 (d) 8.7
  3. 3.Best estimate of 863 ÷ 29? (a) 2900 (b) 29 (c) 290
  4. 4.Best estimate of 1147 ÷ 89? (a) 130 (b) 13 (c) 1300
  5. 5.Best estimate of 6168 ÷ 88? (a) 6900 (b) 69 (c) 690
  6. 6.Best estimate of 991 ÷ 42? (a) 250 (b) 25 (c) 2500
  7. 7.√89 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.4
  8. 8.Best estimate of 2646 ÷ 86? (a) 290 (b) 29 (c) 2900
  9. 9.Best estimate of 3379 ÷ 73? (a) 48 (b) 480 (c) 4800
  10. 10.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.5
  11. 11.Best estimate of 667 ÷ 28? (a) 2200 (b) 220 (c) 22
  12. 12.Best estimate of 3022 ÷ 32? (a) 1010 (b) 101 (c) 10100
  13. 13.√63 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  14. 14.√90 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6
  15. 15.√26 to 1 decimal place? (a) 5.0 (b) 5.3 (c) 5.1 (d) 5.2
  16. 16.Best estimate of 2969 ÷ 82? (a) 37 (b) 370 (c) 3700
  17. 17.Best estimate of 2543 ÷ 36? (a) 640 (b) 64 (c) 6400
  18. 18.√24 to 1 decimal place? (a) 4.9 (b) 4.6 (c) 4.7 (d) 4.8
  19. 19.Best estimate of 3169 ÷ 52? (a) 6300 (b) 630 (c) 63
  20. 20.Best estimate of 2665 ÷ 42? (a) 670 (b) 67 (c) 6700
  21. 21.Best estimate of 1422 ÷ 42? (a) 360 (b) 3600 (c) 36
  22. 22.Best estimate of 1814 ÷ 76? (a) 230 (b) 2300 (c) 23
  23. 23.Best estimate of 3098 ÷ 66? (a) 440 (b) 44 (c) 4400
  24. 24.√29 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.7
  25. 25.Best estimate of 6197 ÷ 72? (a) 890 (b) 8900 (c) 89
  26. 26.√61 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.8
  27. 27.√50 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.3 (d) 7.1
  28. 28.Best estimate of 2406 ÷ 43? (a) 60 (b) 6000 (c) 600
  29. 29.Best estimate of 2825 ÷ 42? (a) 7100 (b) 710 (c) 71
  30. 30.√87 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.2
  31. 31.Best estimate of 2148 ÷ 29? (a) 7200 (b) 720 (c) 72
  32. 32.Best estimate of 871 ÷ 37? (a) 220 (b) 2200 (c) 22
  33. 33.Best estimate of 852 ÷ 31? (a) 280 (b) 28 (c) 2800
  34. 34.√80 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.9 (d) 8.8
  35. 35.Best estimate of 902 ÷ 41? (a) 23 (b) 2300 (c) 230
  36. 36.Best estimate of 626 ÷ 47? (a) 1300 (b) 13 (c) 130
  37. 37.√30 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.7
  38. 38.Best estimate of 634 ÷ 51? (a) 130 (b) 1300 (c) 13
  39. 39.√76 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 9.0 (d) 8.8
  40. 40.√86 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.2 (d) 9.3

Answer key

  1. 9.1
  2. 8.6
  3. 29
  4. 13
  5. 69
  6. 25
  7. 9.4
  8. 29
  9. 48
  10. 6.5
  11. 22
  12. 101
  13. 7.9
  14. 9.5
  15. 5.1
  16. 37
  17. 64
  18. 4.9
  19. 63
  20. 67
  21. 36
  22. 23
  23. 44
  24. 5.4
  25. 89
  26. 7.8
  27. 7.1
  28. 60
  29. 71
  30. 9.3
  31. 72
  32. 22
  33. 28
  34. 8.9
  35. 23
  36. 13
  37. 5.5
  38. 13
  39. 8.7
  40. 9.3

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