Today's entry is an interesting piece of history. It's a page from the company newsletter from C&C Bank School in Chicago. Banking was a bit more thought-intensive in 1925, as computers were still a few decades from being fixtures in banks, and the faster you could do operations on numbers the better. So shortcuts and tricks that helped you do stuff in your head was a must.
Here's a quickie that was discovered by my Grandpa Hattan (1907-1977) when he was just a 17 year-old kid.