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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 239 · 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 1362 ÷ 42? (a) 340 (b) 3400 (c) 34
  2. 2.Best estimate of 4347 ÷ 64? (a) 720 (b) 7200 (c) 72
  3. 3.Best estimate of 3864 ÷ 61? (a) 640 (b) 6400 (c) 64
  4. 4.√71 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.7
  5. 5.Best estimate of 4865 ÷ 62? (a) 81 (b) 810 (c) 8100
  6. 6.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.9 (d) 8.8
  7. 7.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.2
  8. 8.Best estimate of 3567 ÷ 76? (a) 450 (b) 45 (c) 4500
  9. 9.√72 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.4 (d) 8.3
  10. 10.Best estimate of 2200 ÷ 84? (a) 280 (b) 2800 (c) 28
  11. 11.√70 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.7
  12. 12.Best estimate of 1136 ÷ 36? (a) 280 (b) 28 (c) 2800
  13. 13.Best estimate of 2503 ÷ 33? (a) 83 (b) 8300 (c) 830
  14. 14.Best estimate of 3622 ÷ 48? (a) 7200 (b) 720 (c) 72
  15. 15.Best estimate of 1064 ÷ 44? (a) 2700 (b) 27 (c) 270
  16. 16.Best estimate of 2819 ÷ 71? (a) 400 (b) 40 (c) 4000
  17. 17.√41 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.1
  18. 18.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 9.3
  19. 19.Best estimate of 6149 ÷ 81? (a) 7700 (b) 770 (c) 77
  20. 20.√79 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 9.1 (d) 8.9
  21. 21.Best estimate of 1333 ÷ 31? (a) 4400 (b) 44 (c) 440
  22. 22.Best estimate of 495 ÷ 26? (a) 17 (b) 170 (c) 1700
  23. 23.Best estimate of 435 ÷ 23? (a) 220 (b) 2200 (c) 22
  24. 24.Best estimate of 1825 ÷ 38? (a) 46 (b) 4600 (c) 460
  25. 25.√63 to 1 decimal place? (a) 8.1 (b) 7.8 (c) 7.9 (d) 8.0
  26. 26.Best estimate of 2827 ÷ 38? (a) 7100 (b) 71 (c) 710
  27. 27.Best estimate of 2161 ÷ 52? (a) 4300 (b) 43 (c) 430
  28. 28.Best estimate of 2482 ÷ 49? (a) 500 (b) 5000 (c) 50
  29. 29.√38 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.1 (d) 6.2
  30. 30.Best estimate of 5284 ÷ 82? (a) 660 (b) 6600 (c) 66
  31. 31.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.3 (d) 4.4
  32. 32.√32 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 5.7
  33. 33.Best estimate of 1869 ÷ 32? (a) 62 (b) 620 (c) 6200
  34. 34.Best estimate of 6461 ÷ 86? (a) 720 (b) 7200 (c) 72
  35. 35.Best estimate of 1556 ÷ 52? (a) 310 (b) 31 (c) 3100
  36. 36.Best estimate of 2257 ÷ 52? (a) 4500 (b) 45 (c) 450
  37. 37.√87 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.3 (d) 9.1
  38. 38.Best estimate of 2576 ÷ 63? (a) 4300 (b) 43 (c) 430
  39. 39.Best estimate of 6925 ÷ 86? (a) 77 (b) 7700 (c) 770
  40. 40.√31 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 5.7 (d) 5.6

Answer key

  1. 34
  2. 72
  3. 64
  4. 8.4
  5. 81
  6. 8.6
  7. 6.3
  8. 45
  9. 8.5
  10. 28
  11. 8.4
  12. 28
  13. 83
  14. 72
  15. 27
  16. 40
  17. 6.4
  18. 9.1
  19. 77
  20. 8.9
  21. 44
  22. 17
  23. 22
  24. 46
  25. 7.9
  26. 71
  27. 43
  28. 50
  29. 6.2
  30. 66
  31. 4.5
  32. 5.7
  33. 62
  34. 72
  35. 31
  36. 45
  37. 9.3
  38. 43
  39. 77
  40. 5.6

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