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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 101 · 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 2088 ÷ 63? (a) 3500 (b) 350 (c) 35
  2. 2.√61 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 7.7
  3. 3.Best estimate of 6999 ÷ 87? (a) 78 (b) 7800 (c) 780
  4. 4.√59 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.4 (d) 7.6
  5. 5.Best estimate of 2314 ÷ 47? (a) 460 (b) 46 (c) 4600
  6. 6.√38 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  7. 7.Best estimate of 4068 ÷ 67? (a) 580 (b) 58 (c) 5800
  8. 8.Best estimate of 2054 ÷ 51? (a) 410 (b) 4100 (c) 41
  9. 9.Best estimate of 4428 ÷ 84? (a) 55 (b) 5500 (c) 550
  10. 10.√29 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.6 (d) 5.5
  11. 11.Best estimate of 2869 ÷ 84? (a) 360 (b) 3600 (c) 36
  12. 12.Best estimate of 1594 ÷ 72? (a) 23 (b) 2300 (c) 230
  13. 13.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.8
  14. 14.√83 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.3 (d) 9.1
  15. 15.√24 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.6 (d) 4.7
  16. 16.√98 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.1 (d) 9.8
  17. 17.Best estimate of 5297 ÷ 63? (a) 88 (b) 8800 (c) 880
  18. 18.Best estimate of 796 ÷ 54? (a) 1600 (b) 160 (c) 16
  19. 19.Best estimate of 2706 ÷ 31? (a) 900 (b) 90 (c) 9000
  20. 20.Best estimate of 914 ÷ 38? (a) 230 (b) 2300 (c) 23
  21. 21.√65 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 8.2
  22. 22.Best estimate of 6470 ÷ 74? (a) 920 (b) 92 (c) 9200
  23. 23.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  24. 24.Best estimate of 5722 ÷ 66? (a) 82 (b) 8200 (c) 820
  25. 25.√62 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.9 (d) 7.7
  26. 26.Best estimate of 530 ÷ 33? (a) 18 (b) 180 (c) 1800
  27. 27.Best estimate of 1879 ÷ 29? (a) 6300 (b) 63 (c) 630
  28. 28.√92 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  29. 29.Best estimate of 557 ÷ 32? (a) 190 (b) 1900 (c) 19
  30. 30.Best estimate of 6253 ÷ 76? (a) 780 (b) 78 (c) 7800
  31. 31.√69 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.2 (d) 8.3
  32. 32.√80 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.7 (d) 9.0
  33. 33.Best estimate of 2361 ÷ 32? (a) 790 (b) 7900 (c) 79
  34. 34.Best estimate of 1889 ÷ 37? (a) 470 (b) 4700 (c) 47
  35. 35.Best estimate of 4025 ÷ 52? (a) 8100 (b) 81 (c) 810
  36. 36.Best estimate of 2760 ÷ 61? (a) 460 (b) 46 (c) 4600
  37. 37.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 6.3
  38. 38.Best estimate of 1641 ÷ 57? (a) 270 (b) 27 (c) 2700
  39. 39.√84 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.0
  40. 40.√87 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.0

Answer key

  1. 35
  2. 7.8
  3. 78
  4. 7.7
  5. 46
  6. 6.2
  7. 58
  8. 41
  9. 55
  10. 5.4
  11. 36
  12. 23
  13. 8.6
  14. 9.1
  15. 4.9
  16. 9.9
  17. 88
  18. 16
  19. 90
  20. 23
  21. 8.1
  22. 92
  23. 9.8
  24. 82
  25. 7.9
  26. 18
  27. 63
  28. 9.6
  29. 19
  30. 78
  31. 8.3
  32. 8.9
  33. 79
  34. 47
  35. 81
  36. 46
  37. 6.1
  38. 27
  39. 9.2
  40. 9.3

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