The gestation period for an elephant is 640 to 660 days. This is equivalent to about 95 weeks, or 22 months, and is the longest gestation period of any mammal.
Dimes dated after 1964 are copper-nickel clad and contain no silver. Quarters are also clad, except for the bicentennial commemorative coins with an S mint mark that were produced for mint and proof sets. Kennedy half dollars from 1965 to 1970 were 40 percent silver composition. After 1970, all Kennedy halves were clad, except the same S bicentennial issue.
1964 was the date on the last 90% silver coins. Silver coins were actually made up through the early part of 1966 but the 1964 date was used on all of those. 1965 was used on the clad coins that were made in that year. So any dime, half dollar or quarter with a date of 1964 is 90% silver. <br /> <br /> Kennedy Half Dollars produced from 1965 through 1969 were made with a 40% silver content.