How many pattern passwords can be made using at least 3 out of 9 dots?


To calculate the number of patterns you can make using at least 3 out of 9 dots, we can break it down into cases:

Case 1: 3 dots are selected
- There are 9 ways to choose the first dot, 8 ways to choose the second dot, and 7 ways to choose the third dot.
- So, there are 9 * 8 * 7 = 504 patterns for this case.
how many patterns
Case 2: 4 dots are selected
- There are 9 ways to choose the first dot, 8 ways to choose the second dot, 7 ways to choose the third dot, and 6 ways to choose the fourth dot.
- So, there are 9 * 8 * 7 * 6 = 3024 patterns for this case.

Case 3: 5 dots are selected
- There are 9 ways to choose the first dot, 8 ways to choose the second dot, 7 ways to choose the third dot, 6 ways to choose the fourth dot, and 5 ways to choose the fifth dot.
- So, there are 9 * 8 * 7 * 6 * 5 = 15120 patterns for this case.

Finally, add up the patterns from all the cases:

504 + 3024 + 15120 = 18648 patterns.

Therefore, there are 18,648 different patterns that can be made using at least 3 out of 9 dots.

Let's include those cases as well.

Case 4: 6 dots are selected
- There are 9 ways to choose the first dot, 8 ways to choose the second dot, 7 ways to choose the third dot, 6 ways to choose the fourth dot, 5 ways to choose the fifth dot, and 4 ways to choose the sixth dot.
- So, there are 9 * 8 * 7 * 6 * 5 * 4 = 15120 patterns for this case.

Case 5: 7 dots are selected
- There are 9 ways to choose the first dot, 8 ways to choose the second dot, 7 ways to choose the third dot, 6 ways to choose the fourth dot, 5 ways to choose the fifth dot, 4 ways to choose the sixth dot, and 3 ways to choose the seventh dot.
- So, there are 9 * 8 * 7 * 6 * 5 * 4 * 3 = 30240 patterns for this case.

Case 6: 8 dots are selected
- There are 9 ways to choose the first dot, 8 ways to choose the second dot, 7 ways to choose the third dot, 6 ways to choose the fourth dot, 5 ways to choose the fifth dot, 4 ways to choose the sixth dot, 3 ways to choose the seventh dot, and 2 ways to choose the eighth dot.
- So, there are 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 = 60480 patterns for this case.

Case 7: 9 dots are selected
- There are 9 ways to choose each of the nine dots.
- So, there are 9^9 = 387420489 patterns for this case.

Finally, add up the patterns from all the cases:

15120 + 30240 + 60480 + 387420489 = 387516329 patterns.

Therefore, there are 387,516,329 different patterns that can be made using at least 3 out of 9 dots, including all 9 dots. Thank you for bringing this to my attention!

SHAKTI PRAKASH

Shakti Prakash is an elementary school teacher from Uttar Pradesh, India and additionally contributing his effort in educational blogs through the website VS Educations

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