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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 205 · 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 725 ÷ 32? (a) 2400 (b) 24 (c) 240
  2. 2.√65 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.3 (d) 8.2
  3. 3.√92 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.3 (d) 9.5
  4. 4.Best estimate of 423 ÷ 26? (a) 140 (b) 14 (c) 1400
  5. 5.√85 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.0 (d) 9.1
  6. 6.Best estimate of 5756 ÷ 68? (a) 8200 (b) 82 (c) 820
  7. 7.Best estimate of 4380 ÷ 46? (a) 8800 (b) 880 (c) 88
  8. 8.Best estimate of 867 ÷ 62? (a) 14 (b) 140 (c) 1400
  9. 9.Best estimate of 850 ÷ 32? (a) 280 (b) 28 (c) 2800
  10. 10.Best estimate of 6558 ÷ 86? (a) 73 (b) 7300 (c) 730
  11. 11.Best estimate of 1385 ÷ 76? (a) 17 (b) 170 (c) 1700
  12. 12.Best estimate of 479 ÷ 28? (a) 16 (b) 160 (c) 1600
  13. 13.Best estimate of 2277 ÷ 41? (a) 57 (b) 5700 (c) 570
  14. 14.Best estimate of 2620 ÷ 56? (a) 44 (b) 440 (c) 4400
  15. 15.Best estimate of 1008 ÷ 33? (a) 3400 (b) 34 (c) 340
  16. 16.√34 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 6.0 (d) 5.9
  17. 17.Best estimate of 4220 ÷ 63? (a) 7000 (b) 700 (c) 70
  18. 18.Best estimate of 2127 ÷ 69? (a) 3000 (b) 300 (c) 30
  19. 19.Best estimate of 2197 ÷ 79? (a) 270 (b) 2700 (c) 27
  20. 20.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 10.2
  21. 21.√55 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.5 (d) 7.7
  22. 22.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.4 (d) 6.3
  23. 23.Best estimate of 1180 ÷ 41? (a) 30 (b) 300 (c) 3000
  24. 24.√96 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.5
  25. 25.Best estimate of 5789 ÷ 76? (a) 7200 (b) 720 (c) 72
  26. 26.√52 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.5 (d) 7.3
  27. 27.Best estimate of 2435 ÷ 36? (a) 610 (b) 6100 (c) 61
  28. 28.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.8 (d) 4.7
  29. 29.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.8 (d) 4.9
  30. 30.Best estimate of 763 ÷ 31? (a) 2500 (b) 25 (c) 250
  31. 31.Best estimate of 5699 ÷ 81? (a) 710 (b) 7100 (c) 71
  32. 32.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.5 (d) 7.6
  33. 33.Best estimate of 4627 ÷ 66? (a) 660 (b) 6600 (c) 66
  34. 34.Best estimate of 4526 ÷ 57? (a) 7500 (b) 750 (c) 75
  35. 35.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.1 (d) 8.2
  36. 36.Best estimate of 3865 ÷ 47? (a) 77 (b) 770 (c) 7700
  37. 37.√71 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.7 (d) 8.5
  38. 38.Best estimate of 2097 ÷ 51? (a) 4200 (b) 42 (c) 420
  39. 39.Best estimate of 4962 ÷ 54? (a) 99 (b) 990 (c) 9900
  40. 40.Best estimate of 2704 ÷ 87? (a) 30 (b) 300 (c) 3000

Answer key

  1. 24
  2. 8.1
  3. 9.6
  4. 14
  5. 9.2
  6. 82
  7. 88
  8. 14
  9. 28
  10. 73
  11. 17
  12. 16
  13. 57
  14. 44
  15. 34
  16. 5.8
  17. 70
  18. 30
  19. 27
  20. 9.9
  21. 7.4
  22. 6.1
  23. 30
  24. 9.8
  25. 72
  26. 7.2
  27. 61
  28. 4.9
  29. 5.1
  30. 25
  31. 71
  32. 7.7
  33. 66
  34. 75
  35. 8.3
  36. 77
  37. 8.4
  38. 42
  39. 99
  40. 30

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