The post office not only takes care of the incoming mail and distributes it in-house. The team also handles the shipping of letters and parcels. Sometimes, of course, something goes wrong, such as sending invoices to business partners in Brazil, Sweden and Singapore.
Each invoice contained a personal address and should be placed in a large envelope with a sticker and the address of each recipient.
After all: All bills to Brazil arrived in a letter addressed to Brazil. The same was true for the bills in Sweden and Singapore. However, all but one of the exceptions came back because address labels and billing recipients did not agree. The one exception is a bill to Singapore - this was addressed to the right recipient.
"That's really funny," says the head of the post office, as she hears from the mess of bills. "There were so many different ways to bury the bills wrongly, but there are only six different combinations where something like this happens."
How many bills have been sent in total?
Note: The post office manager knows how many bills have been sent to which country. It was at least one per country.