Timeline for How many ten digit decreasing numbers are there when its digits form a decreasing sequence such that each digit is not larger than the preceding one?
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 5, 2018 at 11:11 | vote | accept | Just van der Veeken | ||
| Feb 7, 2018 at 9:09 | |||||
| Feb 4, 2018 at 0:29 | comment | added | Abr001am | done; it's amazing how coincidently happened that this sum is just a deployment of Vandermonde's identity you stated above! | |
| Feb 4, 2018 at 0:26 | history | edited | Abr001am | CC BY-SA 3.0 | added 180 characters in body |
| Feb 4, 2018 at 0:15 | comment | added | N. F. Taussig | In your explanation, you wrote $F_2$ when you meant $F_1$ in your list of cases. Also, you should explain that $\binom{10}{i}$ is the way of selecting $i$ of the $10$ digits to be included in the number and $\binom{9}{i - i}$ is the number of ways of choosing which $i - 1$ of the $9$ possible transition points are used to jump from a smaller digit to the next larger one. That said, it is a nice approach. | |
| Feb 3, 2018 at 23:53 | history | edited | Abr001am | CC BY-SA 3.0 | deleted 56 characters in body |
| Feb 3, 2018 at 23:42 | history | answered | Abr001am | CC BY-SA 3.0 |