d*****n
发帖数: 9 | 1 Choose a number randomly between 1 and 999999 inclusive, all choices
being equally likely. What is the probability that the digits sum up to 23?
For example, the number 7646 is between 1 and 999999 and its digits sum up
to 23 (7+6+4+6=23). | m****y
发帖数: 74 | 2 this boils down to enumerate the ways in which 23 can be decomposed, with
each decomposed element less than 10. should not be hard do this manually... |
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