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1/60 of a trillionth of a min., 4 letters
Infinitesimal division of a min., 4 letters
Infinitesimal fraction of a min., 4 letters
Minute segment of a min., 4 letters
One 60-trillionth of a min., 4 letters
There are 60 trillion in a min., 4 letters
Time it takes for light to travel .3 mm, 4 letters
Time unit for studying the speed of light: Abbr., 4 letters