_:vb6814077 "Why would anyone use sixthing when any (N \u2212 a2) divisible by 6 would also be divisible by 3? The answer is that sometimes the numerator and/or the denominator is simpler in sixthing,"@en . _:vb6814076 . _:vb6814076 "to divide by six, which also means multiplying a denominator by six"@en . _:vb6814077 . "1" . _:vb6814077 "1993, Dead Reckoning: Calculating Without Instruments\u200Ehttps://books.google.ca/books?id=4CivnChLnE0C&pg=PA102, page 102:"@en . .