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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 549 · 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 5651 ÷ 59? (a) 940 (b) 9400 (c) 94
  2. 2.√85 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.0
  3. 3.Best estimate of 750 ÷ 21? (a) 3800 (b) 380 (c) 38
  4. 4.Best estimate of 5131 ÷ 84? (a) 64 (b) 6400 (c) 640
  5. 5.Best estimate of 489 ÷ 27? (a) 1600 (b) 160 (c) 16
  6. 6.Best estimate of 890 ÷ 72? (a) 130 (b) 13 (c) 1300
  7. 7.√80 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  8. 8.Best estimate of 930 ÷ 32? (a) 310 (b) 31 (c) 3100
  9. 9.√84 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.1 (d) 9.0
  10. 10.√41 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.4 (d) 6.6
  11. 11.Best estimate of 3198 ÷ 78? (a) 40 (b) 400 (c) 4000
  12. 12.Best estimate of 3251 ÷ 36? (a) 8100 (b) 81 (c) 810
  13. 13.√50 to 1 decimal place? (a) 7.1 (b) 6.8 (c) 7.0 (d) 6.9
  14. 14.√34 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.9 (d) 5.7
  15. 15.√43 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.6 (d) 6.5
  16. 16.√40 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.4 (d) 6.5
  17. 17.Best estimate of 4624 ÷ 59? (a) 77 (b) 770 (c) 7700
  18. 18.√96 to 1 decimal place? (a) 9.8 (b) 9.5 (c) 9.6 (d) 9.7
  19. 19.√42 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.5
  20. 20.Best estimate of 1177 ÷ 78? (a) 15 (b) 150 (c) 1500
  21. 21.Best estimate of 4130 ÷ 54? (a) 830 (b) 83 (c) 8300
  22. 22.√31 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.6 (d) 5.4
  23. 23.√58 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.9 (d) 7.7
  24. 24.Best estimate of 2733 ÷ 89? (a) 30 (b) 3000 (c) 300
  25. 25.Best estimate of 2860 ÷ 86? (a) 3200 (b) 32 (c) 320
  26. 26.Best estimate of 1450 ÷ 24? (a) 730 (b) 73 (c) 7300
  27. 27.Best estimate of 3238 ÷ 64? (a) 5400 (b) 54 (c) 540
  28. 28.Best estimate of 1541 ÷ 49? (a) 310 (b) 31 (c) 3100
  29. 29.Best estimate of 4435 ÷ 56? (a) 740 (b) 74 (c) 7400
  30. 30.Best estimate of 807 ÷ 22? (a) 4000 (b) 400 (c) 40
  31. 31.Best estimate of 687 ÷ 44? (a) 17 (b) 1700 (c) 170
  32. 32.Best estimate of 2321 ÷ 29? (a) 77 (b) 770 (c) 7700
  33. 33.√37 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  34. 34.√66 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.0 (d) 8.1
  35. 35.Best estimate of 3593 ÷ 49? (a) 72 (b) 7200 (c) 720
  36. 36.Best estimate of 3059 ÷ 37? (a) 76 (b) 760 (c) 7600
  37. 37.Best estimate of 7822 ÷ 82? (a) 98 (b) 9800 (c) 980
  38. 38.Best estimate of 4508 ÷ 68? (a) 6400 (b) 64 (c) 640
  39. 39.Best estimate of 3897 ÷ 67? (a) 5600 (b) 56 (c) 560
  40. 40.Best estimate of 2193 ÷ 47? (a) 440 (b) 44 (c) 4400

Answer key

  1. 94
  2. 9.2
  3. 38
  4. 64
  5. 16
  6. 13
  7. 8.9
  8. 31
  9. 9.2
  10. 6.4
  11. 40
  12. 81
  13. 7.1
  14. 5.8
  15. 6.6
  16. 6.3
  17. 77
  18. 9.8
  19. 6.5
  20. 15
  21. 83
  22. 5.6
  23. 7.6
  24. 30
  25. 32
  26. 73
  27. 54
  28. 31
  29. 74
  30. 40
  31. 17
  32. 77
  33. 6.1
  34. 8.1
  35. 72
  36. 76
  37. 98
  38. 64
  39. 56
  40. 44

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