When slipping around between hotels, the welcome letter envelope carries the incoming day receipts, the checkout envelope is nice for the next days. Always a good excuse for a quiet drink in a corner of the bar to update the day's totals into the small pcket sized (old fashioned) notebook. Saves carrying an electronic lump and looking for a power point, also if the envelopes hit the laundry or whatver you at least have another record. First action on the return flight or train, transpose into the spreadsheet for submission.