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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 840 · 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 1718 ÷ 42? (a) 430 (b) 43 (c) 4300
  2. 2.√23 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 5.0 (d) 4.8
  3. 3.Best estimate of 5458 ÷ 67? (a) 780 (b) 78 (c) 7800
  4. 4.Best estimate of 5862 ÷ 84? (a) 7300 (b) 730 (c) 73
  5. 5.√34 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 5.8
  6. 6.Best estimate of 2683 ÷ 52? (a) 540 (b) 54 (c) 5400
  7. 7.Best estimate of 1646 ÷ 27? (a) 55 (b) 5500 (c) 550
  8. 8.Best estimate of 2279 ÷ 87? (a) 250 (b) 25 (c) 2500
  9. 9.Best estimate of 1899 ÷ 32? (a) 630 (b) 6300 (c) 63
  10. 10.√85 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.4 (d) 9.3
  11. 11.√71 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.3 (d) 8.5
  12. 12.Best estimate of 7360 ÷ 86? (a) 820 (b) 8200 (c) 82
  13. 13.Best estimate of 1377 ÷ 54? (a) 2800 (b) 280 (c) 28
  14. 14.Best estimate of 5560 ÷ 67? (a) 7900 (b) 79 (c) 790
  15. 15.Best estimate of 5008 ÷ 86? (a) 560 (b) 56 (c) 5600
  16. 16.√78 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 8.8 (d) 9.0
  17. 17.Best estimate of 3150 ÷ 88? (a) 3500 (b) 350 (c) 35
  18. 18.√70 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.2
  19. 19.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.4 (d) 6.3
  20. 20.Best estimate of 2273 ÷ 82? (a) 2800 (b) 280 (c) 28
  21. 21.Best estimate of 2405 ÷ 26? (a) 80 (b) 800 (c) 8000
  22. 22.√26 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  23. 23.√89 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4
  24. 24.√79 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 9.2 (d) 8.9
  25. 25.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 7.3
  26. 26.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  27. 27.√32 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 6.0 (d) 5.9
  28. 28.Best estimate of 3734 ÷ 44? (a) 930 (b) 9300 (c) 93
  29. 29.Best estimate of 955 ÷ 21? (a) 4800 (b) 48 (c) 480
  30. 30.Best estimate of 7817 ÷ 87? (a) 87 (b) 870 (c) 8700
  31. 31.√67 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.5 (d) 8.4
  32. 32.Best estimate of 7119 ÷ 86? (a) 7900 (b) 79 (c) 790
  33. 33.Best estimate of 5143 ÷ 78? (a) 6400 (b) 640 (c) 64
  34. 34.√69 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.6 (d) 8.5
  35. 35.Best estimate of 1426 ÷ 33? (a) 480 (b) 4800 (c) 48
  36. 36.√22 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.9 (d) 4.7
  37. 37.√46 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  38. 38.Best estimate of 4751 ÷ 52? (a) 950 (b) 95 (c) 9500
  39. 39.Best estimate of 3756 ÷ 88? (a) 42 (b) 420 (c) 4200
  40. 40.√40 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 6.3

Answer key

  1. 43
  2. 4.8
  3. 78
  4. 73
  5. 5.8
  6. 54
  7. 55
  8. 25
  9. 63
  10. 9.2
  11. 8.4
  12. 82
  13. 28
  14. 79
  15. 56
  16. 8.8
  17. 35
  18. 8.4
  19. 6.1
  20. 28
  21. 80
  22. 5.1
  23. 9.4
  24. 8.9
  25. 7.1
  26. 9.8
  27. 5.7
  28. 93
  29. 48
  30. 87
  31. 8.2
  32. 79
  33. 64
  34. 8.3
  35. 48
  36. 4.7
  37. 6.8
  38. 95
  39. 42
  40. 6.3

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