Think twice next time someone asks you for "five minutes of your time" it could cost you more than you think. A British professor has (36) a mathematical (37) to help people find out exactly how much an hour of their time is worth. Professor Ian Walker of Warwick University (38) the value of time after research showed that over 80 percent of (39) would buy more time if they could (40) it. "Traditionally, wages or salaries have given an (41) of how we are valued at work," Walker, an (42) professor, said in a statement. "However, by looking at salaries against taxation, the cost of living and (43) variations, we can see (44) " The formula could help in making decisions, such as whether to cook a meal or to get a takeaway, or whether to take public transport or a taxi. Visitors to www. barclaycard,co.uk/ timeismoney can (45) by entering their salary, the region where they work and what kind of work they do. For example, for a professional working in London and earning 25, 000 pounds a year, an hour would be worth 6.44 pounds, according to the Web site. Cooking dinner would cost 5.37 pounds - cheaper to get a takeaway, (46) . Brushing your teeth comes at 32 pence--perhaps hard to find someone to do it for you for less.