Age Whose Square Is the Year

Brain Teaser · Easy · Free problem
A man once noticed something remarkable: the square of his current age equaled the current year. He wrote this down in a journal, but the ink was smudged and the entry is now unreadable. You know two things: - He died in 1970. - He did not live longer than 100 years. What was his age when he made the journal entry?

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