This problem can be solved easily by multiplying the time of the life expectancy of the coin with the fraction 1/20. The solution is as follows:
<span>Life expectancy of circulating paper money = 25 years * 1/20 </span><span>Life expectancy of circulating paper money = 1.25 years or 1 and 1/4 years</span>
Look at the number at the end, and if it's 5 or more, round up. the 6 is greater than or equal to 5, so you round up, dropping the six and making the 2 into a 3, giving you 5.13.
