Is Sanskrit difficult to learn ? I think writing should be hard. It is a little bit confused in term of meaning. For example,in Sanskrit,the number for 50 is 40 :-o (http://veda.wikidot.com/sanskrit-numbers)

Btw, these are some similarities of Chinese,Japanese and Thai numbers.

In chinese, the word for 4 is “si/suh” in Thai is
“see” (in Korean is “sa”)
In chinese, the word for 3 is “san/sahn” in Thai is
“sam” (in Japanese is “san”)(and in Korean is “san” )
In chinese, the word for 10 is “shi” in Thai is
“sib” (in Korean is “ship” )