I was crossing over the fact that some three digit (0-9) numbers can be expressed with the equation:
$(n+2m)*10^2 + (n+m)*10^1 + n*10^0 = 3(70m+37n)$
But how would you determine, how many percents of the all three digit numbers from 000 to 999 can be expressed with the equation? As a follow up, I'd like to know if there is a single equation to express rest of the three digit numbers in a similar manner?