How old was mary queen of scots when she took the throne?
Mary, the only surviving legitimate child of King James V of Scotland, was six days old when her father died and she acceded to the throne. She spent most of her childhood in France while Scotland was ruled by regents, and in 1558, she married the Dauphin of France, Francis. Mary was queen consort of France from his accession in 1559 until his death in December 1560. Widowed, Mary returned to Scotland, arriving in Leith on 19 August 1561. Four years later, she married her half-cousin, Henry Stuart, Lord Darnley, and in June 1566 they had a son, James.
How old was mary queen of scots when she took the throne of Scotland?
six days old
Mary, Queen of Scots
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How old was mary queen of scots when she took the throne as queen consort of France?
sixteen-year-old sixteen
Mary, Queen of Scots
https://en.wikipedia.org/wiki/Mary%2C%20Queen%20of%20Scots
When Henry II died on 10 July 1559, from injuries sustained in a joust, fifteen-year-old Francis and sixteen-year-old Mary became king and queen of France
Mary, Queen of Scots
King Henry II of France 
Mary, Queen of Scots
Mary, Queen of Scots, the only surviving legitimate child of King James V of Scotland, was six days old when her father died and she acceded to the throne of Scotland. However, she spent most of her childhood in France while Scotland was ruled by regents. In 1558, she married Francis, the Dauphin of France. Then, when King Henry II of France died on July 10, 1559 from injuries sustained in a joust, fifteen-year-old Francis and sixteen-year-old Mary became king and queen of France. 