What might these inscriptions added to an «Easy Money» board mean?

Question

These inscriptions, for example S153 and P330, appear to have been added to an Easy Money board.

Does anyone know of house rules that might explain their addition?

(click to enlarge images)

Answer 1

The P looks like the payoff value for the mortgage: It's the M value plus 10% (mostly -- it looks like some of the numbers are just approximations to this value or round in arbitrary ways: 175 + 10% is rounded down to 192, while 395 + 10% is rounded up to 435). So: a remedy to having to calculate mortgage payoffs on the fly (and perhaps to avoid arguments over rounding).

The S value is similar: it looks like the B value minus 10%. Perhaps this was a house rule that allowed a player strapped for cash to sell some houses instead of mortgaging the property: selling a house would thus incur a 10% loss.