Archimedes, a greek mathematician and inventor of the second century
b. c., was commissioned by the king of syracuse to find out whether a crown that had been made for the king was fashioned from pure gold or from a mixture of gold and silver, a less expensive metal. archimedes could not use chemical tests, for they would damage the crown, yet he was able to find the answer to the king’s question. how did he carry out the king’s request?

Archimedes used a physical method of identifying if the crown is pure gold or a mixture of gold and silver. He determined the density of the crown and compared it to the density of pure gold and pure silver. By weighing and determining the volume of the crown, he determines the density and compares it to the density of gold. If it does not match, then the crown is a mixture of gold and silver. Also, if we wanted to identify the percentage of the gold and silver in the crown he can use the density of both gold and silver and determine the percentages present in the crown. 

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16- counting by fours