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.
Silver was removed from half dollars in stages: - Up to 1964 they were made of 90% silver. - From 1965 to 1970 they were 40% silver. - After that, they've been made of copper-nickel. In addition, nickels minted from mid-1942 to 1945 contained a small amount of silver due to wartime shortages of nickel.