Hangzhou

=== Hangzhou Summary ===
The Hangzhou numeral system is the only surviving variation of the rod numeral system. The rod numeral system is a positional numeral system used by the Chinese in mathematics. Hangzhou numerals are a variation of the Southern Song rod numerals.
Hangzhou numerals were used as shorthand in number-intensive areas of commerce such as accounting and bookkeeping. At the same time, standard Chinese numerals were used in formal writing, akin to spelling out the numbers in English. Hangzhou numerals were once popular in Chinese marketplaces, such as those in Hong Kong and Chinese restaurants in Malaysia before the 1990s, but they have gradually been supplanted by Arabic numerals. This is similar to what had happened in Europe with Roman numerals used in ancient and medieval Europe for mathematics and commerce. Nowadays, the Suzhou numeral system is only used for displaying prices in Chinese markets or on traditional handwritten invoices.
=== The Black Lotus and Hangzhou Code ===
The gang, Black Lotus, is a gang created in China. 
In the Chinese gang Black Lotus, they used the Hangzhou numerals as a code to communicate with other gang members. The numbers come in pairs. When using the London A-Z book, the first number will be the page number and then the second number will be the word.