This section is from the book "Facts Worth Knowing", by Robert Kemp Philip. Also available from Amazon: Inquire Within for Anything You Want to Know.
2159. Curious properties of the Number Nine. If any row of two or more figures be reversed and subtracted from itself, the figures composing the remainder, will, when added horizontally, be a multiple of nine: = 42 886 3261 18-9X2. 198-9X2. 1638-9X2 2160.
 
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