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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 883 · 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.√62 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 7.9
  2. 2.Best estimate of 1879 ÷ 84? (a) 23 (b) 2300 (c) 230
  3. 3.Best estimate of 1161 ÷ 26? (a) 390 (b) 39 (c) 3900
  4. 4.Best estimate of 2496 ÷ 36? (a) 620 (b) 6200 (c) 62
  5. 5.Best estimate of 3901 ÷ 64? (a) 6500 (b) 650 (c) 65
  6. 6.√37 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.0
  7. 7.Best estimate of 2171 ÷ 34? (a) 7200 (b) 72 (c) 720
  8. 8.Best estimate of 3487 ÷ 54? (a) 70 (b) 7000 (c) 700
  9. 9.Best estimate of 885 ÷ 36? (a) 2200 (b) 22 (c) 220
  10. 10.√69 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.6
  11. 11.Best estimate of 4951 ÷ 66? (a) 71 (b) 7100 (c) 710
  12. 12.√74 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.5 (d) 8.6
  13. 13.Best estimate of 1799 ÷ 62? (a) 300 (b) 30 (c) 3000
  14. 14.√42 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.5
  15. 15.Best estimate of 3338 ÷ 76? (a) 4200 (b) 42 (c) 420
  16. 16.√23 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.0 (d) 5.1
  17. 17.√87 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.5 (d) 9.3
  18. 18.√63 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 8.0 (d) 7.8
  19. 19.Best estimate of 1413 ÷ 29? (a) 470 (b) 4700 (c) 47
  20. 20.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  21. 21.√82 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.2 (d) 9.0
  22. 22.√58 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.7 (d) 7.6
  23. 23.Best estimate of 6836 ÷ 84? (a) 85 (b) 8500 (c) 850
  24. 24.√72 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.6
  25. 25.Best estimate of 2365 ÷ 42? (a) 590 (b) 59 (c) 5900
  26. 26.Best estimate of 6971 ÷ 82? (a) 87 (b) 870 (c) 8700
  27. 27.√78 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  28. 28.Best estimate of 3899 ÷ 81? (a) 4900 (b) 490 (c) 49
  29. 29.Best estimate of 4518 ÷ 82? (a) 560 (b) 56 (c) 5600
  30. 30.√92 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  31. 31.Best estimate of 3896 ÷ 64? (a) 6500 (b) 65 (c) 650
  32. 32.Best estimate of 906 ÷ 32? (a) 300 (b) 3000 (c) 30
  33. 33.√75 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  34. 34.Best estimate of 4161 ÷ 56? (a) 69 (b) 6900 (c) 690
  35. 35.Best estimate of 2889 ÷ 32? (a) 9600 (b) 96 (c) 960
  36. 36.Best estimate of 1519 ÷ 38? (a) 3800 (b) 38 (c) 380
  37. 37.Best estimate of 2021 ÷ 88? (a) 22 (b) 2200 (c) 220
  38. 38.√32 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.8 (d) 5.7
  39. 39.Best estimate of 5376 ÷ 62? (a) 90 (b) 9000 (c) 900
  40. 40.Best estimate of 1390 ÷ 21? (a) 7000 (b) 700 (c) 70

Answer key

  1. 7.9
  2. 23
  3. 39
  4. 62
  5. 65
  6. 6.1
  7. 72
  8. 70
  9. 22
  10. 8.3
  11. 71
  12. 8.6
  13. 30
  14. 6.5
  15. 42
  16. 4.8
  17. 9.3
  18. 7.9
  19. 47
  20. 9.8
  21. 9.1
  22. 7.6
  23. 85
  24. 8.5
  25. 59
  26. 87
  27. 8.8
  28. 49
  29. 56
  30. 9.6
  31. 65
  32. 30
  33. 8.7
  34. 69
  35. 96
  36. 38
  37. 22
  38. 5.7
  39. 90
  40. 70

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