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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 908 · 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.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.6 (d) 9.7
  2. 2.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 6.9 (d) 7.1
  3. 3.Best estimate of 2678 ÷ 28? (a) 89 (b) 8900 (c) 890
  4. 4.Best estimate of 1027 ÷ 33? (a) 340 (b) 34 (c) 3400
  5. 5.√85 to 1 decimal place? (a) 9.0 (b) 9.3 (c) 9.1 (d) 9.2
  6. 6.√29 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.6
  7. 7.√37 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.2 (d) 6.3
  8. 8.Best estimate of 680 ÷ 52? (a) 14 (b) 140 (c) 1400
  9. 9.Best estimate of 2257 ÷ 39? (a) 5600 (b) 56 (c) 560
  10. 10.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 5.2
  11. 11.Best estimate of 2632 ÷ 28? (a) 88 (b) 8800 (c) 880
  12. 12.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  13. 13.Best estimate of 2973 ÷ 31? (a) 990 (b) 99 (c) 9900
  14. 14.√46 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  15. 15.Best estimate of 2840 ÷ 42? (a) 710 (b) 7100 (c) 71
  16. 16.√38 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.2 (d) 6.3
  17. 17.Best estimate of 3249 ÷ 64? (a) 540 (b) 5400 (c) 54
  18. 18.√66 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 8.3
  19. 19.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 6.1
  20. 20.Best estimate of 4147 ÷ 62? (a) 690 (b) 69 (c) 6900
  21. 21.√98 to 1 decimal place? (a) 9.8 (b) 10.1 (c) 9.9 (d) 10.0
  22. 22.√88 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.5
  23. 23.Best estimate of 1857 ÷ 29? (a) 6200 (b) 620 (c) 62
  24. 24.√63 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 7.9
  25. 25.√56 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.6 (d) 7.7
  26. 26.Best estimate of 5412 ÷ 89? (a) 60 (b) 600 (c) 6000
  27. 27.Best estimate of 4075 ÷ 44? (a) 102 (b) 1020 (c) 10200
  28. 28.Best estimate of 4883 ÷ 82? (a) 6100 (b) 61 (c) 610
  29. 29.√32 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.7
  30. 30.Best estimate of 2431 ÷ 46? (a) 490 (b) 49 (c) 4900
  31. 31.Best estimate of 1473 ÷ 21? (a) 740 (b) 7400 (c) 74
  32. 32.Best estimate of 2761 ÷ 56? (a) 4600 (b) 46 (c) 460
  33. 33.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.2 (d) 9.1
  34. 34.√67 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  35. 35.√24 to 1 decimal place? (a) 4.8 (b) 5.1 (c) 5.0 (d) 4.9
  36. 36.√96 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.8
  37. 37.Best estimate of 1845 ÷ 42? (a) 4600 (b) 460 (c) 46
  38. 38.√20 to 1 decimal place? (a) 4.4 (b) 4.5 (c) 4.2 (d) 4.3
  39. 39.Best estimate of 2133 ÷ 52? (a) 430 (b) 43 (c) 4300
  40. 40.Best estimate of 412 ÷ 32? (a) 14 (b) 1400 (c) 140

Answer key

  1. 9.7
  2. 7.1
  3. 89
  4. 34
  5. 9.2
  6. 5.4
  7. 6.1
  8. 14
  9. 56
  10. 5.1
  11. 88
  12. 9.6
  13. 99
  14. 6.8
  15. 71
  16. 6.2
  17. 54
  18. 8.1
  19. 5.9
  20. 69
  21. 9.9
  22. 9.4
  23. 62
  24. 7.9
  25. 7.5
  26. 60
  27. 102
  28. 61
  29. 5.7
  30. 49
  31. 74
  32. 46
  33. 8.9
  34. 8.2
  35. 4.9
  36. 9.8
  37. 46
  38. 4.5
  39. 43
  40. 14

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