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.
Various commemorative coins minted before and after 1964 also contain silver but these were not generally intended for daily circulation. All dimes, quarters, half dollars and dollar coins minted in 1964 and before all contain silver. For the most part, the silver comprises 90% of the weight of the coin. In addition, during the years of World War 2, US nickels also contained silver.