My barber charges $14 per hair cut. Some customers choose to leave a $1 tip. This is an interesting and easy way to gauge customer satisfaction – easy for the customer to round up if they want to, and easy to process. Divide the day’s takings by $14; and the remainder is likely to be the number of satisfied customers. In Excel, the formula is =MOD(takings,14). And yes, I know this does not take into account other variables… Can you expand on this thought and see if we can turn it into a usable technique for other businesses?