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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 202 · 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 5283 ÷ 64? (a) 8800 (b) 88 (c) 880
  2. 2.Best estimate of 4122 ÷ 46? (a) 82 (b) 8200 (c) 820
  3. 3.√35 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 5.7
  4. 4.Best estimate of 3757 ÷ 78? (a) 470 (b) 47 (c) 4700
  5. 5.√46 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.8 (d) 6.9
  6. 6.Best estimate of 970 ÷ 79? (a) 12 (b) 1200 (c) 120
  7. 7.√27 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.2 (d) 5.3
  8. 8.Best estimate of 5677 ÷ 62? (a) 9500 (b) 950 (c) 95
  9. 9.Best estimate of 1341 ÷ 88? (a) 150 (b) 1500 (c) 15
  10. 10.√32 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.6 (d) 5.5
  11. 11.Best estimate of 1775 ÷ 66? (a) 250 (b) 2500 (c) 25
  12. 12.Best estimate of 1328 ÷ 61? (a) 220 (b) 22 (c) 2200
  13. 13.Best estimate of 5107 ÷ 56? (a) 85 (b) 850 (c) 8500
  14. 14.Best estimate of 3432 ÷ 49? (a) 6900 (b) 69 (c) 690
  15. 15.√67 to 1 decimal place? (a) 8.2 (b) 8.5 (c) 8.4 (d) 8.3
  16. 16.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  17. 17.√69 to 1 decimal place? (a) 8.3 (b) 8.0 (c) 8.1 (d) 8.2
  18. 18.√37 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.0 (d) 6.1
  19. 19.√88 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.6
  20. 20.Best estimate of 1134 ÷ 77? (a) 1400 (b) 140 (c) 14
  21. 21.√80 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.8 (d) 8.7
  22. 22.√55 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.4 (d) 7.7
  23. 23.Best estimate of 1243 ÷ 42? (a) 310 (b) 3100 (c) 31
  24. 24.√43 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.6 (d) 6.4
  25. 25.√83 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.4
  26. 26.√53 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.4 (d) 7.3
  27. 27.√87 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.4
  28. 28.Best estimate of 4286 ÷ 46? (a) 860 (b) 86 (c) 8600
  29. 29.Best estimate of 1714 ÷ 24? (a) 8600 (b) 860 (c) 86
  30. 30.Best estimate of 5750 ÷ 66? (a) 820 (b) 8200 (c) 82
  31. 31.Best estimate of 4590 ÷ 57? (a) 7700 (b) 770 (c) 77
  32. 32.Best estimate of 2678 ÷ 34? (a) 8900 (b) 890 (c) 89
  33. 33.√52 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.4 (d) 7.2
  34. 34.Best estimate of 3741 ÷ 43? (a) 940 (b) 9400 (c) 94
  35. 35.Best estimate of 726 ÷ 38? (a) 1800 (b) 180 (c) 18
  36. 36.Best estimate of 2124 ÷ 34? (a) 71 (b) 710 (c) 7100
  37. 37.Best estimate of 2176 ÷ 76? (a) 27 (b) 2700 (c) 270
  38. 38.Best estimate of 894 ÷ 21? (a) 4500 (b) 45 (c) 450
  39. 39.√65 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  40. 40.Best estimate of 2712 ÷ 31? (a) 90 (b) 900 (c) 9000

Answer key

  1. 88
  2. 82
  3. 5.9
  4. 47
  5. 6.8
  6. 12
  7. 5.2
  8. 95
  9. 15
  10. 5.7
  11. 25
  12. 22
  13. 85
  14. 69
  15. 8.2
  16. 9.6
  17. 8.3
  18. 6.1
  19. 9.4
  20. 14
  21. 8.9
  22. 7.4
  23. 31
  24. 6.6
  25. 9.1
  26. 7.3
  27. 9.3
  28. 86
  29. 86
  30. 82
  31. 77
  32. 89
  33. 7.2
  34. 94
  35. 18
  36. 71
  37. 27
  38. 45
  39. 8.1
  40. 90

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