Years lived before 1921: Three
Years lived after 1921: Ninety-nine
Katherine Johnson (Left) Barack Obama (Center) Willie Mays (Right)
2015 Medal of Freedom ceremony at White House
Years lived before 1921: Zero
Years lived after 1921: Ninety-Five
John Glenn entering Friendship 7.
In 1962, multiple fledgling IBM computers were determining the trajectory of the Friendship 7 from take off to splashdown. John Glenn who, like many astronauuts of his era, was weary of putting his life in the hands of computing machines, asked that Katherine Johnson do all the calculations manually and said "if she says they're good, then I'm ready to go." The rest is NASA history.
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