[obm-l] sistema decimal e inducao

[Faelccmm@xxxxxxx]

Ola pessoal, 


Fiquei em duvida nestes 2 problemas:


1) It is impossible to *reverse* a number by multiplying it by 2. In other words,there is no number of the form abcd, for example, such that abcd x 2 = dcba.That holds true for all numbers, not just four-digit ones. 
However,there is a three-digit number abc in base 8 such that abc x 2 = cba. Can you find that number? 

2) If,in a room with n people (n>=2), every person shakes hands once with everyother person, prove that there are (n^(2)-n)/2 handshakes.