Someone told me that each equation I included in my book would halve the sales. I did put in one equation, Einstein's famous equation, E = MC squared. I hope that this will not scare off half of my potential readers.
Source: A Brief History in Time.
-- Stephen Hawking, (Jan 8 1942-2018), English physicist, educator, author; He used black holes to help explain universal physical laws in A Brief History of Time, 1987.