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3 votes

Save now! All the digits at half the price

A bit messier than I'd like, but here goes. As other answers have noted, the doubleable PD10 numbers we want are those where Let's show that every such number can be specified by: for an overall ...
  • 24.5k
2 votes

Save now! All the digits at half the price

Other reasoning, same result:
  • 6,847
7 votes
Accepted

Save now! All the digits at half the price

Let's define some terms: Now we can begin. Let's break the problem down now. Now for the final count!
5 votes

Save now! All the digits at half the price

My guess is: First, observe that the first digit of $x$: Then, the reasoning goes this way: I'm not 100% sure of my calculus but this is how I did it:
  • 51
8 votes

Important Alien Message

Not an answer. Alphabetic transcription of alien writing: QBADFAHGCAEBACDABEA FIJCHAEGADFAIEAAHA DGBACAFEILIAGADBAAA AAAFCEADHAGBNEAIFAB HDGAIEFAGCHAFADMEF AHCABIADACHEGADBAO AHDACFIEAHDBAGEIAH ...
  • 1,278
22 votes
Accepted

Find the lower 8-digits number such that

Solution (0 allowed) Reasoning Solution (0 disallowed) Reasoning
  • 130k
6 votes
Accepted

Equilibrium of differences

(NB: I've chosen to interpret "the four numbers Alice chooses must be non-repeatable" as "Alice cannot choose the same digit more than once". There are other possible ...
  • 71.5k

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