At the aforementioned k-man took only imperceptible offense at
Y-san's mainly-innocent comment. But he did retire brieflly to the library to concoct
some good-natured revenge on the lady. Returning moments later to the main room
he found her in conversation with Rainman, and he put to them a puzzle of his own:
I've put a number into a sealed envelope here, he said, and it looks like this.
And he showed them the sequence ABCDCBA. But of course my copy has numbers
for the letters, he explained.
I'm going to tell Y-san the sum of the seven digits, and I'll tell Rainman their product.
Bonanova is not the only one who can resurrect an old puzzle form - you may already
have seen puzzles of this type. It will be helpful if you have. You can discuss
what you know between yourselves, but be careful not to disclose too much.
First to come up with my seven-digit number gets a coveted bonanova gold star.
Then k-man added, here's a clue: 9 >= A >= B >= C >= 0. and 9 >= D >= 0.
Y-san spoke first, to Rainman: I have only a faint clue about what your number is.
I have an even worse idea of what yours is, Rainman replied, this is difficult.
I know, Y-san mused. At this point, your number is still uncertain.
Rainman replied, now I know k-man's number!
What is it?