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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 854 · 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.√67 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  2. 2.Best estimate of 4892 ÷ 63? (a) 8200 (b) 82 (c) 820
  3. 3.Best estimate of 807 ÷ 36? (a) 200 (b) 20 (c) 2000
  4. 4.Best estimate of 801 ÷ 46? (a) 1600 (b) 160 (c) 16
  5. 5.√65 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.4
  6. 6.Best estimate of 1325 ÷ 31? (a) 440 (b) 4400 (c) 44
  7. 7.√37 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.3 (d) 6.2
  8. 8.√72 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.2
  9. 9.Best estimate of 5344 ÷ 83? (a) 6700 (b) 670 (c) 67
  10. 10.√79 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 8.7
  11. 11.Best estimate of 1554 ÷ 69? (a) 22 (b) 2200 (c) 220
  12. 12.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.3 (d) 7.1
  13. 13.√41 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.6
  14. 14.√42 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.6 (d) 6.8
  15. 15.√61 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 8.1
  16. 16.√90 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.2 (d) 9.3
  17. 17.√31 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.3
  18. 18.Best estimate of 2496 ÷ 34? (a) 83 (b) 8300 (c) 830
  19. 19.√83 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 9.2
  20. 20.Best estimate of 342 ÷ 23? (a) 170 (b) 17 (c) 1700
  21. 21.Best estimate of 2453 ÷ 26? (a) 8200 (b) 820 (c) 82
  22. 22.Best estimate of 1371 ÷ 52? (a) 2700 (b) 270 (c) 27
  23. 23.Best estimate of 4164 ÷ 62? (a) 690 (b) 69 (c) 6900
  24. 24.Best estimate of 7491 ÷ 88? (a) 8300 (b) 83 (c) 830
  25. 25.Best estimate of 566 ÷ 36? (a) 140 (b) 1400 (c) 14
  26. 26.√21 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  27. 27.Best estimate of 4004 ÷ 63? (a) 6700 (b) 670 (c) 67
  28. 28.Best estimate of 3512 ÷ 57? (a) 590 (b) 5900 (c) 59
  29. 29.Best estimate of 2516 ÷ 63? (a) 420 (b) 42 (c) 4200
  30. 30.√34 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.7 (d) 5.6
  31. 31.Best estimate of 4248 ÷ 48? (a) 850 (b) 85 (c) 8500
  32. 32.Best estimate of 3723 ÷ 64? (a) 62 (b) 6200 (c) 620
  33. 33.Best estimate of 6194 ÷ 81? (a) 7700 (b) 770 (c) 77
  34. 34.Best estimate of 3887 ÷ 67? (a) 560 (b) 5600 (c) 56
  35. 35.√35 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 5.9 (d) 6.1
  36. 36.√70 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.5
  37. 37.Best estimate of 3237 ÷ 43? (a) 810 (b) 8100 (c) 81
  38. 38.Best estimate of 346 ÷ 26? (a) 120 (b) 12 (c) 1200
  39. 39.Best estimate of 2491 ÷ 77? (a) 31 (b) 3100 (c) 310
  40. 40.√59 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.6 (d) 7.8

Answer key

  1. 8.2
  2. 82
  3. 20
  4. 16
  5. 8.1
  6. 44
  7. 6.1
  8. 8.5
  9. 67
  10. 8.9
  11. 22
  12. 7.1
  13. 6.4
  14. 6.5
  15. 7.8
  16. 9.5
  17. 5.6
  18. 83
  19. 9.1
  20. 17
  21. 82
  22. 27
  23. 69
  24. 83
  25. 14
  26. 4.6
  27. 67
  28. 59
  29. 42
  30. 5.8
  31. 85
  32. 62
  33. 77
  34. 56
  35. 5.9
  36. 8.4
  37. 81
  38. 12
  39. 31
  40. 7.7

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