Convert from dong [Vietnam] to X unit

Unit Definition (dong [Vietnam])
The đồng (VND) is the standard unit of currency used in Vietnam. It has a symbol ₫. It is subdivided into 10 hào, which are divided into 10 xu. The hào and xu units of currency are so worthless that they are no longer issued.

Unit Definition (X unit)
The X-unit (symbol xu) is a unit of length formerly used to measure the wavelength of X-rays and gamma rays. The X-unit is approximately 1.0021×10-13 metre. Defined by the Swedish physicist Karl Manne Georg Siegbahn (1886-1978) in 1925, the X-unit could not at that time be measured directly; the definition was instead made in terms of the spacing between planes of the calcite crystals used in the measuring apparatus.