Convert from tatami to kattha [Nepal]

Unit Definition (tatami)
The tatami is a Japanese unit of area equal to the area of a traditional tatami mat, 0.5 ken by 1 ken or about 90 centimeters by 180 centimeters (roughly 1.62 square meters or 17.5 square feet). This unit, used especially for measuring the area of rooms in houses and apartments, is also called the jo.

Unit Definition (kattha [Nepal])
The kattha is a traditional unit of land area in South Asia, equal to 20 dhurs or 1/20 bigha. Like the bigha, the kattha varied in size from one region to another. In Nepal, where the unit is still in use, the kattha equals about 338 square meters or 442 square yards.