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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 575 · 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.√76 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.9 (d) 8.8
  2. 2.Best estimate of 780 ÷ 29? (a) 2600 (b) 26 (c) 260
  3. 3.Best estimate of 7583 ÷ 88? (a) 8400 (b) 84 (c) 840
  4. 4.√79 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.9 (d) 8.7
  5. 5.Best estimate of 1565 ÷ 81? (a) 200 (b) 20 (c) 2000
  6. 6.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.0 (d) 5.1
  7. 7.Best estimate of 617 ÷ 41? (a) 15 (b) 150 (c) 1500
  8. 8.Best estimate of 1979 ÷ 42? (a) 4900 (b) 49 (c) 490
  9. 9.Best estimate of 1806 ÷ 77? (a) 2300 (b) 230 (c) 23
  10. 10.Best estimate of 8152 ÷ 88? (a) 91 (b) 9100 (c) 910
  11. 11.Best estimate of 1054 ÷ 29? (a) 3500 (b) 350 (c) 35
  12. 12.Best estimate of 2727 ÷ 43? (a) 680 (b) 6800 (c) 68
  13. 13.Best estimate of 304 ÷ 21? (a) 150 (b) 15 (c) 1500
  14. 14.√65 to 1 decimal place? (a) 8.0 (b) 8.3 (c) 8.1 (d) 8.2
  15. 15.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.8 (d) 8.1
  16. 16.√48 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.0 (d) 7.1
  17. 17.√38 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.3 (d) 6.1
  18. 18.Best estimate of 2172 ÷ 71? (a) 310 (b) 3100 (c) 31
  19. 19.√34 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.8 (d) 5.7
  20. 20.Best estimate of 3108 ÷ 69? (a) 4400 (b) 440 (c) 44
  21. 21.√32 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.8 (d) 5.7
  22. 22.√96 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.9
  23. 23.Best estimate of 7598 ÷ 86? (a) 84 (b) 8400 (c) 840
  24. 24.Best estimate of 3371 ÷ 48? (a) 67 (b) 670 (c) 6700
  25. 25.Best estimate of 1463 ÷ 32? (a) 4900 (b) 490 (c) 49
  26. 26.Best estimate of 4450 ÷ 74? (a) 6400 (b) 64 (c) 640
  27. 27.Best estimate of 1091 ÷ 38? (a) 27 (b) 270 (c) 2700
  28. 28.√46 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.1 (d) 7.0
  29. 29.Best estimate of 4140 ÷ 62? (a) 6900 (b) 690 (c) 69
  30. 30.Best estimate of 1153 ÷ 87? (a) 1300 (b) 130 (c) 13
  31. 31.Best estimate of 6404 ÷ 84? (a) 80 (b) 800 (c) 8000
  32. 32.√86 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.4 (d) 9.2
  33. 33.Best estimate of 1337 ÷ 38? (a) 330 (b) 3300 (c) 33
  34. 34.Best estimate of 926 ÷ 32? (a) 310 (b) 3100 (c) 31
  35. 35.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.2
  36. 36.Best estimate of 1370 ÷ 43? (a) 3400 (b) 34 (c) 340
  37. 37.√42 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.3
  38. 38.√69 to 1 decimal place? (a) 8.2 (b) 8.5 (c) 8.4 (d) 8.3
  39. 39.Best estimate of 1476 ÷ 49? (a) 300 (b) 3000 (c) 30
  40. 40.Best estimate of 2094 ÷ 26? (a) 7000 (b) 700 (c) 70

Answer key

  1. 8.7
  2. 26
  3. 84
  4. 8.9
  5. 20
  6. 5.1
  7. 15
  8. 49
  9. 23
  10. 91
  11. 35
  12. 68
  13. 15
  14. 8.1
  15. 8.1
  16. 6.9
  17. 6.2
  18. 31
  19. 5.8
  20. 44
  21. 5.7
  22. 9.8
  23. 84
  24. 67
  25. 49
  26. 64
  27. 27
  28. 6.8
  29. 69
  30. 13
  31. 80
  32. 9.3
  33. 33
  34. 31
  35. 7.3
  36. 34
  37. 6.5
  38. 8.3
  39. 30
  40. 70

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