For those who know what to look for, they could walk into this corner convenience store and discreetly inform themselves of the day’s exchange rate without openly advertising their intention of changing money. At the same time, the shop needn’t reveal its offering of this (technically) extra-legal service. How intention to exchange is then expressed is entirely up to the wiles/guiles of the exchanger, though it is interesting to observe different individuals’ and groups’ strategies.
If you are in a culture or context where the currency one is paid in is not the currency one uses for day-to-day purchases, what is the behavior around currency exchange? Is it the male, traditional breadwinner, who takes charge of exchanging on behalf of a family? Does the woman, the family’s money-manager, take the responsibility? Is exchanging money “macho”? Is changing money an aspirational activity? Is it a low-status task, something to be tasked to a servant?
Also, do patterns of wear on these calculator buttons grant any insight into currency values? The “direction” of exchange?